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By Tim Blythman Decoder Base Station Using DCC Remote Controller DCC Booster So far in this series we have produced a DCC Decoder, Base Station and a Remote Controller unit for the Base Station. The logical progression is a DCC Booster to supply more current and power the track in independent sections. We can also use it as an Automatic Reverse Loop Controller and Image source: https://unsplash.com/photos/a-model-train-on-a-track-with-a-bridge-in-the-background-ADYqbbcjsyk even a Simple Base Station. DCC Booster and Reverse Loop Controller A DCC Booster allows the expansion of a DCC system by providing an extra driver supplying more current than can be delivered by a single Base Station. It should have current sensing to allow it to isolate faults such as short circuits on the track. Another handy thing to have in a DCC system is a reverse loop controller. Certain track arrangements can be prone to short circuits due to the train bridging the circuits of the two tracks. If your track has a so-called balloon loop or three-way Y junction, it will probably benefit from a reverse loop controller. In October 2012, we published the Reverse Loop Controller For DCC Model Railways (see siliconchip.au/ Features & Specifications 🛤 Compact unit fits in a UB5 Jiffy Box 🛤 Simple LED indications 🛤 Optional detailed OLED display 🛤 DCC Booster mode 🛤 Reverse Loop Controller mode 🛤 Simple Base Station mode 🛤 Trip current adjustable in 100mA steps up to 9.9A 🛤 Track voltage: standard range of 8-22V 🛤 Track current: up to 10A (5A with DC jack input) siliconchip.com.au Article/494). That design used a relay to switch the polarity of an existing DCC track signal. By adding polarity control to our DCC Booster, we can combine these functions into a single unit that can provide the automatic polarity switching and offer extra current drive for the track. Thus, the DCC Booster also becomes the Reverse Loop Controller. We have chosen to implement these features with a microcontroller, which makes it possible to generate a DCC signal. Rather than adding a complex user interface, this unit can simply be connected to a DCC Remote Controller to provide the packets that are to be sent to the track. So this unit can also be used as a Simple Base Station. While it has multiple functions, we will refer to the subject of this article as the Booster, or the Simple Base Station when it is working in base station mode. The earlier project in this series will continue to be known as the Base Station. The completed unit you see in the photos can operate standalone, but the bare board is well-suited to being installed under a control panel or similar. All modes can be configured to power on automatically, so there is no need for such boards to be accessible once they are set up. We envisage these units might be used in a layout with multiple Boosters and/or Reverse Loop Controllers. We’ll focus on building the complete DCC PROJECT KITS DCC Decoder, December 2025 (SC7524, $25) includes everything in the parts list DCC Base Station, January 2026 (SC7539, $90) includes everything in the parts list, except for the case, power supply, glue and the CON4 & CON5 headers DCC Remote Controller, February 2026 (SC7552, $35) includes all required parts, except for the UB5 case and wire/cable DCC Booster & Reverse Loop Controller (SC7579, $45) includes all required parts, except for the Jiffy box, OLED screen, power supply and front panel. The OLED screen (SC7484, $7.50) and front panel (SC7578, $5.00) are available separately. Australia's electronics magazine March 2026  49 Fig.1: this circuit has much in common with the Base Station and serves much the same purpose, since it can also behave as a Simple Base Station. The CON1 DCC input allows it to receive and repeat DCC signals. standalone unit in an enclosure and allow experienced readers the freedom to utilise the bare board as they see fit. Circuit details The Booster circuit (Fig.1) has much in common with the DCC Base Station. IC1 is the PIC16F18146 microcontroller that controls the circuit. Although it can work with a 5V supply, we have chosen to use 3.3V to maintain compatibility with the Remote Controller, which needs a 3.3V supply. IC1 receives 3.3V power at its pins 1 and 20, with these and pins 4, 18 and 19 also connecting to ICSP (in-circuit serial programming) header CON6. IC1’s supply is bypassed by a 100nF capacitor, while a 10kW resistor pulls pin 4 (MCLR) up to allow normal operation unless overridden by a programmer. Like the Base Station, the main DCC 50 Silicon Chip output is driven by a pair of BTN8962 half-bridge drivers, IC2 & IC3, which are controlled from pins 6, 7 & 8 of IC1 via 1kW series resistors. The resistors are provided to limit the current flowing into the microcontroller if there is a serious fault. The DCCOUTEN line is pulled low by a 100kW resistor to shut down both drivers until driven by the micro. The DCC output is available at screw terminals CON2 and also drives bi-­ colour LED1 via its 2.2kW series resistor. The 100nF capacitors provide local bypassing for IC2 and IC3. The IS pins of the drivers source current in proportion to the driver output current, so the IS currents are combined by dual diode D1 and passed through a 1kW resistor to convert the current to a voltage. This voltage is then smoothed by the 10kW resistor and 100nF capacitor. It goes to pin 15 of IC1 (ANC1) to allow Australia's electronics magazine it to be sensed. Pin 15 is both an ADC (analog-to-digital converter) input and an input to a comparator internal to IC1. The ADC is used to measure this current and also the supply voltage noted earlier. We’ll get to the comparator feature shortly. The incoming DCC signal comes in at CON1 and connects to pins 3 and 5 on IC1 via 100nF capacitors and 10kW series resistors. The resistors limit the current that can flow into the microcontroller, while the capacitors allow the incoming DCC to ‘float’ at a different reference voltage. They AC-couple the signal, with DC biasing by the protection diodes internal to the micro. I/O pins 2, 9 and 10 are connected to tactile switches S1-S3 and are supplied with internal pullup currents by IC1. The switches connect to ground, so they pull those pins low when the buttons are pressed. Status indicator siliconchip.com.au LED2 is driven by IC1’s pin 11 digital output via its series resistor. Pins 14 and 16 of IC1 connect to MOD1, an I2C OLED module, while pins 12 and 13 connect to CON5, an RJ45 socket intended to connect to a Remote Controller. These two pins also have 2.2kW pullup resistors to the 3.3V rail. Pins 12, 13, 14 and 16 go to four jumper headers on JP1, with the other pins on JP1 connected to ground. There are a few different firmware modes, but the main distinction is that the OLED module and RJ45 socket cannot be used at the same time as JP1, since the pins would conflict. Basically, JP1 provides some configuration options in the absence of the OLED screen. Power supply The incoming power supply circuitry is much the same as the DCC Base Station too, with DC jack CON4 in parallel with screw terminals CON3. The power comes through fuse F1 to the nominal 15V rail bypassed by a 1000μF capacitor. Like the Base Station, the 15V rail can actually be between 8V and 22V. Diode D2 is connected in reverse across the supply rails to blow the fuse in the event of reverse polarity being applied. A 10kW:1kW divider with a 1μF capacitor across the lower leg is used to reduce the supply voltage to a level that can be measured by a 3.3V microcontroller at its ANA2 analog input (pin 17). So far, this is all practically identical to the Base Station. LED3 is connected across the 15V rail with a series resistor for power indication. A simple linear regulator and its 100μF capacitor provide the 3.3V rail for the microcontroller and associated circuitry, since this unit We recommend starting construction with the two driver ICs, IC2 and IC3. Note the fuse located on the rear of the PCB for easy access in case it blows. does not require as much current on the logic-level rail. If you are using this unit as a Booster or Reverse Controller, your power supply voltage should be similar to that of your Base Station and able to provide enough current for your purposes. You might use a 5-10A supply for a Booster. Above 5A, use the CON3 screw terminals, since CON4 can’t safely handle more than 5A. A Reverse Loop Controller might not need as much current, since it could be just powering a section of track big enough to handle a single train. It might be reasonable to piggyback it off the supply that is powering the Base Station in this case, but you would need to take care with the current limits. There’s no harm in picking a bigger supply, since the current limit can be set lower. The Booster draws around 25mA on its 3.3V rail when the OLED is operating. With a 12V supply, you should be able to add one or two Remote Controllers to a Simple Base Station before the dissipation is more than the 500mW that REG1’s TO-92 case can handle. Internal logic Newer microcontrollers like the PIC16F18146 have a vast array of peripherals; in fact, there are probably more peripherals available than pins to route them to! The internal CLC (configurable logic cell) unit allows pins and other peripherals to be connected via logic elements. We used the CLC in the Digital Boost Regulator from December 2022 (siliconchip.au/ Article/15588). Once configured, the CLC operates completely independently of the processor. Fig.2 shows the equivalent logic that is implemented in the CLC in this project. We have included the comparator, which is a separate peripheral to the CLC. We use three of the four available CLC instances for this project. The upper circuit with the comparator is used in all modes and at all times. Note that the black labels refer to the lines marked in Fig.1. The blue labels are signals internal to the microcontroller; in effect, they do not require an external pin, and are controlled by software or other peripherals. For example, the latch can be set or cleared (with the SET SIGNAL or RESET SIGNAL) to manually switch on or off the DCCOUTEN line and thus the DCC drivers. The comparator output is one of 40 internal signals that can be routed to the CLC input array. It’s even possible to use CLC outputs as inputs to other instances to create more complex logic. Fig.2: the black labels refer to signals in Fig.1, while the blue signals are internal to the microcontroller. This shows the PCB fitted with all parts except the OLED module. The LEDs and tactile switches should be installed with the front panel in place so they can be accurately aligned. siliconchip.com.au Australia's electronics magazine March 2026  51 The DCC Booster/Reverse Loop Controller fits in a compact Jiffy box or can be used as a bare board if needed on a large layout (with the front panel affixed to a hole in your layout’s control panel to integrate it). Adding a Remote Controller unit allows it to operate as a Simple Base Station. Note that the photo shown above is not at actual size. Table 1 – modes and construction options Mode Parts to be omitted Notes Booster with no display OLED and header, RJ45 socket, S3 Reverse Loop Controller with no display OLED and header, RJ45 socket, S3 Leave off the OLED, RJ45 socket and S3 if you are only planning to use the modes without a display. Booster with display RJ45 socket, JP1 Reverse Loop Controller with display RJ45 socket, JP1 Simple Base Station with display CON1 (DCC in), JP1 To allow the option of using any of the modes with a display, all parts should be fitted except JP1. At least one DCC Remote Controller is needed to use the Simple Base Station mode. Depending on how you want to use this project, you can assemble the board without some of the parts, as indicated here. Table 2 – jumper settings for modes without an OLED screen JP1a (REV) JP1b (+1) JP1c (+2) JP1d (+4) Notes OFF Booster mode operating; LED2 will flash once at startup ON Reverse Loop Controller mode operating; LED2 will flash twice at startup OFF OFF OFF Current limit is 1A ON OFF OFF Current limit is 2A OFF ON OFF Current limit is 3A ON ON OFF Current limit is 4A OFF OFF ON Current limit is 5A ON OFF ON Current limit is 6A OFF ON ON Current limit is 8A ON ON ON Current limit is 10A Without the OLED, JP1a sets the mode while the others define the current limit. 52 Silicon Chip Australia's electronics magazine For clarity, the representations in Fig.2 are simplified versions of the logic. For example, the DAC voltage is actually applied to the non-inverting input of the comparator, and the comparator is configured with an inverted output to achieve the behaviour shown in the diagram. The multiplexer is implemented with an AND-OR gate arrangement. The DAC on this chip has an 8-bit resolution and is configured to use a 2.048V reference, so the DAC OUTPUT can be set in 8mV steps (2048mV ÷ 256). The voltage at DCCOUTI changes in proportion to the current supplied by the driver ICs, with 8mV corresponding to steps of around 80mA. The arrangement shown in Fig.2 means that when the current exceeds the set point, the comparator output goes high, the latch is reset and the drivers are disabled much more quickly than if the checks were done in software. The software can read the state of the DCCOUTEN line to report the fact that a trip has occurred. The second circuit is used to swap the polarity of the DCC signal when the reverse loop controller is active. If POLARITY is low, DCCINA controls DCCOUTA and DCCINB controls DCCOUTB. If POLARITY is high, the two multiplexers swap these, effectively flipping the DCC signal polarity (relative to the input). We have briefly touched on the need for this in previous DCC articles, but now we have the opportunity to examine a concrete example. The top of Fig.3 shows a so-called balloon loop. The train would typically enter on the left and pass around the loop clockwise before exiting at left, but it could travel in the opposite direction. The problem is that the wheels that travel on the outside of the loop (contacting DCCOUTA) come in contact with DCCINA when entering and DCCINB when exiting. This may only be brief, but it is typical that all wheels along one side of a locomotive are joined together to improve current collection from the track. The triangle junction below also shows this problem. So the Booster must detect the conflict and toggle the polarity when the wheels bridge rails that are of opposing polarities. In practice, if it detects an overcurrent condition (such as might be caused by a short circuit), it toggles the polarity; if the fault persists, siliconchip.com.au the power trips off momentarily. If flipping the polarity clears the fault, all is well. The multiplexer circuit is also used to feed the DCC signal from CON1 to CON2 when the circuit is operating in booster mode. In this case, the polarity is fixed at ‘0’ so that DCCINA drives DCCOUTA and DCCINB drives DCCOUTB. Firmware There are five distinct operating modes that the Booster firmware can run in. When it starts up, the mode is fixed until the next time the processor is reset or restarts. Table 1 lists the five modes and the parts that can be omitted during construction if you intend to use only that mode. You can refer to the parts list for other options. There is no reason that all parts cannot be fitted, but remember that any jumper shunts that are installed will conflict with the respective pins on the OLED display and RJ45 socket. Since there are Booster and Reverser modes that can use the display, the most flexible option is to fit the OLED module and leave off the header for JP1. Each mode is fixed at startup, so the firmware is effectively broken down into five different subprograms. Some of them share functions; for example, the two reverse loop controller modes share a common routine that checks whether the comparator has been triggered and decides whether to flip the polarity or shut the power off for the trip period. In the modes with no display, JP1 is used for setting the mode and trip current. We’ll get into more details about how the modes work once the unit is assembled. Note that pushbutton S3 need not be fitted in the modes that do not have a display, since it is used to escape from these modes. The first header on JP1 (JP1a) is used to set whether the booster or reverse loop controller mode is run; having the jumper on selects reverse loop controller mode. After this, the three remaining jumpers allow eight combinations and thus eight trip-current settings. We have programmed them for 1, 2, 3, 4, 5, 6, 8 and 10 amps. Table 2 summarises these selections. Holding S1 or S2 during startup will change the EEPROM setting that determines whether the DCC output is started automatically when power is applied. During operation, S1 and S2 siliconchip.com.au will switch the output on or off, and LED2 will reflect this state. During startup without the OLED module, LED2 also lights, flashing once for Booster mode and twice for Reverse Loop Controller mode. Display Since the jumper shunts are not available if a display is fitted, S3 is used to access different menus that can be used to alter the settings. The normal display screen shows the mode, supply voltage and DCC output (CON2) current. There is also a description of the state that can indicate, amongst other things, if an over-current trip has occurred. We will look at these screens later once construction is complete. Unless you are building several Boosters or Reverse Loop Controllers that will be hidden from sight, such as being distributed around a large layout, we recommend that you build the version with the display. The display means that more information is available for troubleshooting, and the settings allow the mode to be easily changed if you do want to try them out. If you are using the Booster as a Simple Base Station, you must have the display fitted. To accompany a Simple Base Station, you will also need to build at least one of the DCC Remote Controllers, since these will provide the DCC packets that are sent to the track. If no packets are received on the RJ45 socket, idle packets will be sent out to ensure there is always valid data on the track. Construction We’ll cover assembly of the main PCB listing the parts that we have fitted Fig.3: this balloon loop is one example of a track layout that means a reverse controller is needed. The three-way triangle junction is another common example; note how a train taking the curve on the left requires a different relative polarity to a train taking the curve on the right. Australia's electronics magazine March 2026  53 Figs.4 & 5: the PCB for this project has a mix of SMD and through-hole parts on both sides, so pay attention and watch the orientations of the polarised parts. to our prototype, which is everything in the Parts List, so skip fitting any parts that you’ve determined you don’t need. The main PCB, coded 09111248 and measuring 45 × 79mm, will have SMD parts fitted to the back, then the front, followed by most of the throughhole components. Figs.4 & 5 are the overlay diagrams for the PCBs that you can use as a guide during assembly. The LEDs and switches depend on the front panel for alignment, so temporarily attach the panel and use it to align these parts when you are fitting them. A header is used for the OLED module to provide extra height, and so that it can be detached if needed. For the SMD parts, we suggest having the standard SMD gear on hand, including flux paste, a fume extractor, a magnifier, solder wicking braid and some tweezers. Start by fitting IC2 and IC3, the driver ICs. You may need to turn up your iron or apply extra heat from a hot air tool, since they sit on large copper areas on the PCB. Add flux to the pads and rest one of the driver ICs in place. Tack one of the smaller leads and adjust it to get the position right. Then solder the large tab in place, keeping the iron on the part until the solder flows freely along the width of the tab. Give the solder a moment to harden, then solder the remaining smaller pins. Fit the other driver IC after that. Follow with IC1, the microcontroller, being sure to align the pin 1 marking with that on the PCB. Tack one lead, align the part and then solder the remaining leads. Solder the BAT54C diode next to IC1 using the same technique. Four of the 100nF capacitors are on this side, along with the only 1μF part. Solder these next. Ten of the resistors are also on this side of the PCB. They will be printed with codes that correspond to their values (eg, 1kW = 102 or 1001). Flip the PCB over and solder the other two 100nF capacitors and carefully work through the remaining six resistors. Next, mount the fuse holder to the back of the PCB. This location allows it to be easily accessed without having to fully disassemble the unit. It helps to fit the fuse while soldering, since this will align the pins and ensure that the tabs are correctly orientated, too. Next, solder the through-hole parts except the OLED and its headers, the LEDs and the tactile switches. We’ll fit these later while aligning them to the enclosure and front panel. Work upwards in order of height. Fit D2 with its cathode stripe orientated as shown, then solder it and trim its leads flush with the PCB. If you need to fit JP1 or the CON6 ICSP header, do so next. Follow with any of CON1, CON2, CON3 and CON4 that you need, ensuring the terminal block entries face the outside of the board. Also solder in the two electrolytic capacitors and REG1, being careful to observe their polarities. Be sure to bend the leads of the 1000μF part correctly; the longer lead is positive. Then, snap the RJ45 socket (CON5) into place and carefully solder its leads. At this stage, the PCB is complete enough to allow IC1 to be programmed Our prototype has all components fitted, but you should refer to Table 1 and the parts list to check which are able to be left off. 54 Silicon Chip Australia's electronics magazine siliconchip.com.au if required. Microcontrollers bought from our Online Shop, including in kits, come pre-programmed. If you need to program it, power can be supplied from CON3, CON4 (eg, 12V at the DC jack) or 3.3V from the programmer via the ICSP header. If you are only using the modes that do not require the display, you are probably not too concerned about using the panel PCB and you will probably have specific ideas about fitting the Booster as part of an existing panel; perhaps running flying leads to the LEDs and switches. Remember that you do not need to install S3 if a display is not fitted. LEDs through their holes in the panel and solder them in place. We found that 17mm tactile switches (which are about the longest that are easily available) only just clear the panel if mounted flat. We were able to get some extra height by raising them slightly off the PCB before soldering. Our kits include 18mm switches so that should not be necessary. Take off the panel and attach the socket header to the OLED module’s pins and place that onto the PCB. Refit the panel, secure it and use it to align the OLED module before soldering its pins too. Hardware Fig.6 shows the cutting and drilling needed to fit the assembly into a UB5 Jiffy box, while Fig.7 is a 3D render of the case, so you can check that you are working on the correct faces of the box. The round hole for the DC jack can be made with a drill. We prefer to drill a small pilot hole with a twist drill and then enlarge that with a step drill. The vertical cuts can be made using a fine saw. Use a sharp blade to score the horizontal lines, and then the tab can be carefully snapped off using wide-nosed pliers. Take care with the slots for CON1 and CON2 since they are only separated by a thin tab of plastic, which can be easily snapped off accidentally. If you are mounting the unit in a case with a display, we suggest fitting the tapped spacers to position the panel PCB and align the LEDs and tactile switches. The relatively long 16mm tapped spacers are only needed to achieve clearance for the RJ45 socket. Fit the spacers on the top side of the PCB, secured from behind with machine screws. Thread the switches and LEDs into their holes and then attach the panel PCB with the remaining machine screws. Watch the polarity of LED2 and LED3, but note that the polarity of LED1 does not matter due to the alternating DCC signal. Now you can accurately position the Cutting and drilling The slots for CON1 and CON2 will align with the internal bosses for PCB mounting (which are not used in this project). So it might take some extra effort to snap the plastic, since it will be thicker in these locations. Finally, fit the PCB and panel assembly into the case and secure it with the screws that are supplied with the case. Operation with no display The initial setting of the Booster and Reverse Loop Controller is to operate in the mode that does not require a display. Since the jumper shunts are only checked when the micro starts up, which will typically be when power is applied, it’s a good idea to power off the Booster, change the jumpers and then reapply power. Booster mode (with the REV jumper left off) will cause LED2 to flash once. When the REV jumper is fitted, LED2 will flash twice at startup and the Reverse Loop Controller is started. You can also set whether the CON2 DCC output is enabled at power-on by holding in S1 (on) or S2 (off) during startup. S1 and S2 are used to switch the DCC output on or off during normal operation. You’ll need a valid DCC signal of some sort applied to CON1. Otherwise, LED2 will flash at 1Hz. If this is flashing with a low duty cycle or is Fig.6: to create a standalone device, you can cut a UB5 Jiffy box as shown here and use our 09111249 PCB as a front panel. Fig.7: you can check the locations of your cuts against this diagram. If you are building this project as a Simple Base Station, you can omit CON1 and the corresponding panel cutout. siliconchip.com.au Australia's electronics magazine March 2026  55 Screen 1: the screens are simple and provide a handy amount of information, including supply voltage and DCC track current. Screen 2: the trip current can be set in steps of 100mA. The figure at upper right is the raw DAC setting calculated by the microcontroller. Screen 3: the current measuring offset that is applied by the BTN8962 driver ICs can be manually adjusted on this page. Screen 4: the offset can also be automatically determined on this screen. Note that this will require track power to be shut off. Screen 5: if the AUTOPOWER setting is enabled, the DCC track output drivers will be active as soon as power is applied. Screen 6: the main operating mode can be set here. NO OLED refers to the first two modes listed in Table 1. Screen 7: since the mode is only checked at startup, this page can be used to reset and restart the microcontroller after a mode change. Screen 8: in Booster mode, the word BOOST is shown and ERROR might be displayed if a valid DCC signal is not detected. Screen 9: the Reverse Loop Controller mode shows REV as the mode, as well as a symbol to indicate whether the polarity has been flipped. fully off, the DCC output at CON2 is off. Flashing with a high duty cycle or being fully lit means that the DCC output is enabled. LED1 is powered directly from the DCC signal, so should be lit up both red and green (appearing yellow) if the DCC output is on. If only one colour is showing on LED1, then there may be a wiring fault or a problem with the DCC signal. If LED2 is lit and LED1 is off and flickering on briefly, there is probably a short circuit caused by the trip limit being exceeded. With everything operating normally, both LED1 and LED2 should be either solidly on or solidly off. The current-measuring offset parameter can be automatically calibrated. To do this, short the lower left pad of S3 to ground or press S3 if it is fitted. The DCC output will shut off and LED2 will flicker for two seconds, after which the calibration runs. If all is well, LED2 will light up for a second and switch off. Otherwise, no changes are made. The offset can vary with supply voltage, so it’s a good idea to use your normal operating supply while performing this calibration. These indications are quite terse; the messages shown on the OLED are more helpful, so let’s have a look at those modes next. Most of the settings shown on the OLED screen are also used in the modes that do not use the OLED, so it is possible to temporarily fit an OLED for setup purposes and then remove it later. followed by an offset value, which should be around 4A, but could be anywhere between 1A and 9A. If there is a problem, try again and check your construction in case there are any problems. This can also be manually configured using a similar process to the Base Station from Part 2 of this series. Use Screen 2 to set the TRIP limit to 9A and Screen 3 to set the OFFSET to 0A. Cycle back to Screen 1 and press S1 to switch on the DCC output. Note the displayed current and change the Screen 3 OFFSET to that value. If you return to Screen 1, the displayed current should now be zero. Use S2 to switch off the DCC output and reset the TRIP limit to a suitable value, such as 5A or lower if the controller is being powered from the DC jack. If the OFFSET is not between 1A and 9A, there may be a construction problem. Screen 5 allows you to set the DCC output to switch on automatically at startup. The settings on Screens 3, 4 and 5 are also used in headless mode, so temporarily fitting an OLED module is a way of setting up the Booster with confidence. Let’s have a look at the individual modes. 56 Silicon Chip Display modes Before attempting to use the modes that use the OLED display, make sure that no shunts are fitted to JP1. Don’t connect anything to CON2 (DCC OUT) yet. To enable the display, power on the Booster while holding down S3. LED2 will flash until S3 is released. The unit should then start in the Simple Base Station mode with the display active. Once you have activated the display, you should see something like Screen 1, which is the main operating screen for the Simple Base Station. Screens 2-7 are the various settings that can be accessed by pressing S3 (SEL). Press S3 to get to Screen 6 and select a different mode (BASE STN, BOOSTER or REVERSER). Then press S3 to get to Screen 7 and press S1 to restart the micro. This will ensure that the new mode is properly configured and will be loaded at startup. If you need to go back to one of the ‘headless’ modes, choose NO OLED on Screen 6 and then perform a reset on Screen 7. Remember to detach the OLED after that, so it doesn’t affect the jumpers. Settings Configure the current measuring offset parameter on Screen 4 by pressing S3. The display will show OK, SET Australia's electronics magazine Simple Base station mode You will need a DCC Remote Controller connected to use the Booster to provide DCC track data. Screen 1 should show an asterisk (*) at upper siliconchip.com.au right when packets are received, and the Remote Controller should be allocated a host index, as if it were connected to a Pico-2-based DCC Base Station. Switch on the DCC output with S1 and switch it off with S2 from the main screen. LED2 will indicate what the last action was. The text on the screen will show ON or OFF, or TRIP if the current limit has been reached. You should now be able to control your DCC locomotives through the DCC Remote Controller interface. The commands to control track power (on the DCC Remote Controller) should also work. Booster With the OLED fitted and enabled, you will also have access to the Screen 2-7 menu items, as well as the Booster features seen in Screen 8. Screen 8 is very similar to Screen 1. You might also see the ERROR message, which means that the Booster has not detected a valid DCC signal at the CON1 DCC input connector. In this case, the DCC output shuts off, since it would otherwise continue to supply power to the track with no control signals. If you are operating without a display, LED2 will flicker on or off briefly once per second to indicate that the DCC signal has been lost. Of course, LED1 will not be lit either. Reverse Loop Controller Reverse Loop Controller mode operates in much the same fashion as Booster mode (see Screen 9). Here, the symbol on the right shows whether the polarity is normal or reversed. Silicon Chip kcaBBack Issues $10.00 + post $11.50 + post $12.50 + post $13.00 + post $14.00 + post January 1997 to October 2021 November 2021 to September 2023 October 2023 to September 2024 October 2024 onwards September 2025 onwards All back issues after February 2015 are in stock, while most from January 1997 to December 2014 are available. For a full list of all available issues, visit: siliconchip.com. au/Shop/2 PDF versions are available for all issues at siliconchip.com.au/Shop/12 We also sell photocopies of individual articles for those who don’t have a computer In operation, you will see LED2 flicker off very quickly when the polarity is swapped. If the OLED is not in use, the indications on the LEDs will be identical to that noted in the previous section. Considerations The Booster and Reverse Loop Controller modes both work by reading and then recreating the incoming signal using the driver ICs. This can be contrasted with the earlier Reverse Loop Controller for DCC Model Railways, which fed through signal through directly but used a relay to flip its polarity when required. There is an approximately 3μs delay in the signal propagating through the BTN8962 driver ICs. The logic in the PIC microcontroller also adds a small delay, but this is of the order of tens of nanoseconds; negligible compared to the drivers. This means that using a DCC track signal to drive the input of the Booster or Reverse Loop Controller will result in a noticeable amount of signal skew between two adjacent track sections, enough to cause a potential short circuit due to one driver pulling the track section high while another has already started pulling the other low, or vice versa. One way to avoid this is to use the logic-level signals from the Pico-2based Base Station instead of the track signals, before they are delayed by passing through the driver ICs on that board. That way, the track signals coming from the Base Station and Booster/Reverse Loop Controller will have more-or-less synchronous edges. Fig.8 shows where you can tap off the logic level signals from the Base Station to connect to the CON1 DCC signals on the Booster (the blue and green wires). Note that these are the points that connect to pin 2 (IN) of the IC2 & IC3 driver ICs. Thus, any skew caused by the driver ICs should be the same. We found that using the logic-level signals worked better when the circuit grounds are connected; this may not Fig.8: we recommend tapping the logic level DCC signals from the points on the Base Station shown here if you are building this project as a Booster or Reverse Loop Controller, since it will better synchronise the DCC signals that are sent to the track. siliconchip.com.au Australia's electronics magazine March 2026  57 Silicon Chip Binders REAL VALUE AT $21.50* PLUS P&P Are your copies of Silicon Chip getting damaged or dog-eared just lying around in a cupboard or on a shelf? Can you quickly find a particular issue that you need to refer to? Keep your copies safe, secure and always available with these handy binders These binders will protect your copies of S ilicon C hip . They feature heavy-board covers, hold 12 issues & will look great on your bookshelf. H 80mm internal width H Silicon Chip logo printed in goldcoloured lettering on spine & cover Silicon Chip Publications PO Box 194 Matraville NSW 2036 Order online from www. siliconchip.com.au/Shop/4 or call (02) 9939 3295 and quote your credit card number. *see website for delivery prices. 58 Silicon Chip Parts List – DCC Booster 1 double-sided green PCB coded 09111248 measuring 45 × 79mm 1 black panel PCB coded 09111249 measuring 83 × 53 × 0.8mm 1 UB5 Jiffy box 3 M3 × 16mm tapped spacers 6 M3 × 5-6mm blackened machine screws 2 2-way 5mm/5.08mm pluggable screw terminal blocks (CON1, CON2) [Altronics P2592 + P2512, Jaycar HM3102 + HM3122, or Dinkle 2EHDRC-02P + 2ESDV-02P] 1 2-way 5mm/5.08mm screw terminal (CON3; optional in place of CON4) 1 PCB-mounting DC barrel jack (CON4) 1 RJ45 PCB-mount through-hole socket (CON5; optional•) 1 5-way 0.1in (2.54mm) pitch header strip (CON6; optional, for ICSP) 2 M205 fuse clips (F1) 1 M205 fuse to suit PSU; maximum of 5A if CON4 is used, 10A if CON3 is used (F1) 1 2×4-way 0.1in (2.54mm) pin header (JP1; optional•) 4 0.1in (2.54mm) jumper shunts (JP1; optional•) 1 0.91in (23mm) I2C OLED module (MOD1; optional•) 1 4-way 0.1in (2.54mm) socket header strip (optional•, to suit MOD1) 3 through-hole tactile switches with stems 18mm above PCB (S1-S3) (shorter stems can be used if you do not wish to fit the unit inside an enclosure) 1 power supply unit (PSU) to suit Semiconductors 1 PIC16F18146-I/SO microcontroller programmed with 0911124D.HEX (IC1) [Silicon Chip SC7580] 2 BTN8962TA half-bridge drivers, TO-263-7 (IC2, IC3) 1 LP2950ACZ-3.3 3.3V LDO linear regulator, TO-92 (REG1) 1 BAT54C dual common-cathode SMD schottky diode, SOT-23 (D1) 1 1N5404 or 1N5408 3A silicon axial diode, DO-27 (D2) 1 3mm bicolour red/green LED (LED1) 1 3mm green LED (LED2) 1 3mm red LED (LED3) Capacitors (M3216/1206 X7R 50V unless specified) 1 1000μF 25V radial electrolytic 1 100μF 16V radial electrolytic 1 1μF 6 100nF Resistors (M3216/1206, ⅛W ±1%) 1 100kW 6 10kW 3 2.2kW 6 1kW • optional parts depending on intended use; see Table 1 automatically be the case if the Base Station and Booster are powered from separate power supplies. We’ve included an extra GND pad on the Booster for this purpose. You could use the unused CON3 or CON4 GND pad on Base Station to make this connection and use a gauge of wire that is suitable for your track current. Summary The DCC Booster/Reverse Loop Controller provides the drivers and some logic to implement a DCC Simple Base Australia's electronics magazine Station, Booster or Reverse Loop Controller in a compact UB5 case. It has a fast-acting digitally adjustable current limit that makes use of the newer features in modern 8-bit PICs. It can accept a DCC signal at logic levels, so it could be used as a component of a larger DCC system based on commercial hardware, or even a custom base station generating DCC signals. The interface for the Remote Controller provides another means for DCC signals to be provided in the form SC of serial data. siliconchip.com.au