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Into special effects photography? Or want to be? Try this TIME DELAY PHOTOFLASH TRIGGER by Jim Rowe Want to try your hand at ‘stop motion’ photography, where dynamic events such as a match bursting into flame, a drop splashing into a container of liquid or a projectile passing through a light globe, are captured at a crucial moment? Here’s a project designed specifically for this kind of work. It lets you trigger your electronic flash at the precise moment for a great picture. 62  Silicon Chip siliconchip.com.au Who let the smoke out? 30ms after we smashed the light globe by hitting it with a metal weight (that’s it on the right) the filament is only now starting to realise it's lost half of its bulb and is starting to burn up, with flame and smoke. This is a combined time exposure (hence the warm glow from the lamp) and flash shot using the delayed trigger (hence the white pieces of glass). Believe it or not, this was the first shot we took – and a dozen light globes later, we decided it was the best! H ave you been intrigued by those impressive photos capturing the crown-shaped splash when a drop falls into a dish of milk or the tip of a chameleon’s tongue when it’s attaching itself to a flying insect? Or a light bulb shattering as a bullet enters it? These are the kinds of shots which can be achieved using ‘stop motion’ photography. You don’t need much gear to take these shots. The main requirement is a camera with a very fast shutter speed or an electronic flash. Either way you need an electronic triggering unit to either open the camera shutter release, or fire the flash automatically in response to a reference event – such as a sound (like a ‘bang’ or ‘click’) or a contact closure (like the contacts in a PIR motion sensor). The electronic triggering unit must have an accurately adjustable delay time. This allows you to set the camera or flash triggering to occur not just automatically in response to the reference event, but a known period of time after it. siliconchip.com.au So if you predict that the crucial event you want to capture occurs about 40ms (milliseconds) after the reference event (eg, the bang or click, or contact closure), you can set the triggering delay to 40ms and see if this gets the shot. If it then turns out that the shot was a little early or late, you can either reduce or increase the delay to get the precise result. So that’s the rationale behind this project. It’s an automatic electronic shutter release/flash trigger unit with a delay time which can be adjusted in 1ms steps from 0 to 999ms or al- ternatively, in 10ms steps from 0 to 9.99 seconds. Triggering can be from an electret microphone (to pick up sound ‘events’) or other devices like a PIR (passive infrared) motion sensor, lightbeam interrupter system, or custom sensor switches such as microswitches attached to machinery. It is housed in plastic case which on the front panel (lid of case) has three rotary switches to set the time delay, a sensitivity control for the microphone/preamp, an “arm” button, toggle switches to turn on power and to select the time delay, a red LED to Specifications Trigger inputs: Delay time: Timing Accuracy: Outputs: Power: Consumption: electret microphone or external trigger (via PIR sensor etc) 0 to 999ms in 1ms increments or 0 to 9.99 seconds in 10ms increments 1ms or 10ms (1) Non-delayed triggering for external shutter release (2) Delayed triggering for electronic flash 9V alkaline battery 16mA (standby); 30mA when triggered. February 2009  63 (IC7c) TRIGGER GATED TRIGGER PULSE + ELECTRET MIC IN OR GATE MIC PREAMP & SQUARER S ARM S5 SENSITIVITY TRIGGER GATE (FF1) R CONTROL FLIPFLOP 1 (FF2) Q S Q R CONTROL FLIPFLOP 2 Q Q RESET FF1 ENABLE DELAY COUNTER CONTACTS INPUT RESET DELAY COUNTER GATE ENABLE DELAY COUNTER MR DECADE COUNTER 3 38kHz CRYSTAL OSCILLATOR MR + CLOCK UNITS S6 DECADE COUNTER 2 DIVIDER CHAIN (1/380 OR 1/38) S3 END OF DELAY TIME 0 9 PULSE STRETCHER, SCR DRIVER S2 0 NAND GATE (D1-D3, IC8d) 9 10ms (100Hz) OR 1ms (1kHz) show that the unit has been triggered and a green LED to show that the flash or shutter has been fired. Along the top side of the case are four sockets which connect an electret microphone, an external trigger (eg, PIR sensor), the electronic flash and, if required, the electronic camera shutter. How it works The block diagram of Fig.1 shows how it works. It has four states: the ‘waiting’ state – powered on; the ‘armed’ state where the unit is waiting for a triggering input; the ‘triggered’ state where the time delay is counting through and finally the ‘fired’ or ‘ready’ state where the time has elapsed and the unit has fired the electronic flash or electronic shutter. When FF2 is in its reset state (Q-bar high) the circuit is in the ‘ready’ state but when the flipflop is triggered and switches to its set state (Q high) this swings the circuit into its ‘triggered’ state. When the circuit is first turned on, FF2 is reset and so the circuit is in the ‘waiting’ state. The flipflop’s Q-bar output is high , the Q output is low and as a result LED1 is turned on to show that the circuit is ‘ready’ for action. 64  Silicon Chip 9 MR DECADE EN COUNTER 1 CK S1 0 A logic high is also applied to the MR (master reset) inputs of decade counters 1-3, forcing them all to reset with their ‘0’ outputs high. At the same time because FF2’s Q output is low, the EN (enable) input of counter 1 is held low, preventing the counters from operating. The only other part of the circuit which operates in this ‘ready’ state is the 38kHz crystal oscillator and divider chain which runs all the time because it’s used to generate the delay timing pulses. The divider chain is programmed by a switch (S6) to divide the crystal frequency by either 380 times or 38 times, to give timing pulses of either 100Hz (10ms) or 1kHz (1ms) respectively. These pulses are fed to the CK (clock) input of counter 1 but while the circuit is in the ready state the counters can’t respond. Trigger gating When a sound is picked up by the plug-in electret microphone, the mic signal is amplified and ‘squared up’ in the preamp/squarer section, then inverted and fed to one input of the OR gate. The output of the OR gate is then fed via a differentiator circuit and an inverter to one input of a NAND gate – trigger gate IC7c. The other input of this gate is connected to the Q output of control flipflop 1 (FF1), which is used to ensure that only one trigger pulse can get through to trigger FF2. The trigger gate is only ‘open’ when FF1 is set, by briefly pulling its S-bar input low using the ‘ARM’ pushbutton S5. The Q output then switches high, bringing the second input of the trigger gate high and thus allowing a trigger pulse to pass through and reach the S-bar input of FF2. This flipflop is therefore triggered, switching to the set state – with the Q output switching high and the Q-bar output switching low. So the circuit now swings into its ‘triggered’ state. But notice that as soon as the Q-bar output of FF2 switches low, this immediately pulls down the R-bar (reset) input of FF1, resetting this again and causing its Q output to switch low. This closes the trigger gate, ‘disarming’ the circuit to prevent any further triggering until S5 is pressed again, to re-arm it. Note that this triggering action can also be produced by the closing of a set of contacts connected to the circuit’s EXT TRIG input, instead of a sound being picked up by the electret microphone. siliconchip.com.au N–CHANNEL FET TRIGGERED LED2  SHUTTER RELEASE OUTPUT CON2 READY  LED1 FLASH TRIGGER OUTPUT CON3 SCR Fig.1: block diagram of the TimeDelay Photoflash Trigger breaks the circuit down into its various functions. Compare this with the circuit diagram overleaf. The second input connects directly to the lower input of the OR gate, so the logic low produced by the contact closure is again able to pass through the gating and trigger FF2. A number of other things happen once the circuit switches into its ‘triggered’ state. For a start, when the Q-bar output of FF2 switches low this causes triggered LED2 to be turned on via an inverter, to indicate that the circuit has switched into its ‘triggered’ state. At the same time the N-channel FET is turned on, to produce a very low resistance across the ‘shutter release’ output connector (CON2). So if your camera has the facility for remote control of the shutter, it can be automatically opened. At the same time because FF2’s Q output has switched high, LED1 is turned off to show that the ‘ready’ state has ended. The reversal of FF2’s outputs in the triggered state has another important effect, because it means not only that the logic high is removed from the MR inputs of the three decade counters, so they are no longer held reset, but also that a logic high is now applied to the EN input of counter 1, so it can begin counting the timing pulses. Counting starts immediately, with the outputs of counter 1 going high in sequence for each timing pulse (ie, the ‘units’), and then the outputs of counters 2 and 3 going high in sequence for each 10 pulses (‘tens’) and each 100 pulses (‘hundreds’). This counting operation continues until the counter 1 output selected by S1, the counter 2 output selected by S2 and the counter 3 output selected by S3 are all high at the same time. Because the three switches are connected to the inputs of a NAND gate, it’s only when they are all high together that the output of this gate switches low. When this occurs, the resulting negative-going pulse is fed back to the R-bar (reset) input of FF2, causing it to be immediately reset. The decade counters are now disabled and held in their reset state, so counting stops and the circuit is switched back to its ‘ready’ state. At the same time, the negativegoing pulse from the NAND gate is fed through a pulse stretcher and driver to turn on the SCR (silicon controlled rectifier). The SCR conducts, and triggers your electronic flash unit via the diode bridge and trigger output socket (CON3). To sum up, the settings of switches S1, S2 and S3 allow you to directly program the time delay between input It’s all assembled onto a single PC board with the three time-setting switches, pot and LEDs pointing upwards so they can poke through the front panel. We removed switch S5 to pull the unit apart for this photo (its two extension wires are still on the PC board) and of course switch S4 is not normally at quite such a drunken angle! siliconchip.com.au February 2009  65 470 K 4.7k 100 F 220k ELECTRET MIC IN 220nF D5 4.7nF 10k AUDIO SQUARER 10M 10k 22k 8 5 10k 7 IC9b 6 CON1 IC9: LM358 2.2M 2 220k C B 3 Q4 BC338 E 1 IC9a 10k A 4 110k 1 F AUDIO PREAMP 470 +9V VR1 50k SENSITIVITY 12 16 Vdd 11 O9 15 9 MR O8 6 O7 5 O6 IC6 4017B O5 1 10 O4 7 14 CP0 O3 4 O2 2 O1 3 13 O0 CP1 Vss 100nF O5-9 22 F EXT TRIG CONTACTS 100 1nF +9V CON4 COUNTER CLOCK GENERATION 16 100nF Vdd SC S6 9 IC11 SB 10 4053B 11 TP2 12 IC1f 10 2 13 IC3c 14 ZA 12 11 6 100nF +9V +9V 12 Vee Vss 7 8 IC3a 100Hz OR 1kHz 9 14 9 IC1c 1 Vdd (RESET) 6 2 11 11 X1 38kHz 27pF SC IC1e 3 330k O1 MR O2 O4 10 10 CP O5 D2 K A O7 4 O8 7 O9 TP1 O10 TPG Vss 8 O11 +9V 9 7 (2) 6 (4) 5 (8) 3 (16) 12 13 12 14 (32) 3 (64) 4 6 IC3b (256) 5 7 15 1 PROGRAMMABLE FLASH TRIGGER DELAY 66  Silicon Chip 16 Vdd 11 O9 15 9 MR O8 6 O7 5 O6 IC4 4017B O5 1 10 O4 7 14 CP0 O3 4 O2 2 O1 3 13 O0 CP1 100Hz OR 1kHz Vss 100nF O5-9 2 IC2 4040B O6 4 38kHz 27pF O0 O3 IC1b 2.2M 2009 TENS S2 8 IC1: 4069UB IC1a 100nF 16 100nF 8 IC1d 5 16 Vdd 11 O9 15 9 MR O8 6 O7 5 O6 IC5 4017B O5 1 10 O4 7 14 CP0 O3 4 O2 2 O1 3 13 O0 CP1 Vss O5-9 E 1 8 2 A 8 12 13 SA 1ms D1 K 3 1 SB 15 ZB 14 CLOCK UNITS 5 TPG IC3: 4073B SA SC 4 ZC 13 10ms HUNDREDS S3 UNITS S1 D3 K A 8 Fig.2: the circuit is essentially an audio preamp and shaper plus a counter which controls either a flash trigger and/or (if available) a camera shutter after a user-set time delay. siliconchip.com.au S4 +9V 4.7k Q 3 S5 IC10b 5 IC7d 10k Q 3 2 100nF 6 14 1 2 ARM 13 IC10: 4011B 14 1 TRIGGER ON/OFF IC10a 100k E B A IC7b 5 7,8,9 12,13 8 11 IC7c Q 4 100  K 6 10 TRIGGERED LED2 SHUTTER RELEASE D 7 Q5 2N7000 G 1k 9 12 9V BATTERY C IC7a IC7: 4093B 4 470 F 16V Q2 PN200 S CON2 COUNTER ENABLE COUNTER RESET 4.7k COUNT GATE ENABLE 10k E B END OF COUNT A Q3 PN200 C  READY LED1 K 10k 12 13 IC8: 4093B IC8d 2 7 PULSE STRETCHER 10k 3 C B IC8a IC8b 5 100nF 14 1 11 E 4 1k D4 IC8c SCR1 C106D G K A 9 D9 A K 6 10 680 Q1 BC338 2.2k 8 K K D6 A A K K D8 D7 A A C106D K PN200 D6-D9: 1N4004 A K B C triggering and output flash triggering. This means that if you set S3 for zero hundreds, S2 for two tens and S1 for five units, the flash triggering will be delayed by 25ms (using 1ms timing pulses) or 250ms (using 10ms pulses). Circuit details The full circuit is shown in Fig.2. The 38kHz crystal oscillator is based on inverter IC1a, whose output is buffered by IC1e to drive IC2, the 4040 counter and IC1b which makes 38kHz pulses available at test point TP1. Gates IC3b, IC3c and IC3a together with triple CMOS switch IC11 (a 4053B) are used to configure IC2 for division by either 380 or 38 times, to provide the option of timing pulses siliconchip.com.au CON3 10nF D1-D5: 1N4148 A FLASH TRIGGER E BC338 LEDS K A 2N7000 B E G C with a frequency of either 100Hz (38,000/380) or 1kHz (38,000/38). The division ratio is determined by switch S6, which controls the state of SA/SB/ SC inside IC11. The resulting timing pulses are then sent to pin 13 of IC4 (which corresponds to decade counter 1 in Fig.1), and also made available at test point TP2 via buffer IC1f. In the section of the circuit at upper left, you’ll see the electret mic input socket CON1 plus the mic preamp and squarer circuitry based around op amps IC9b and IC9a, the LM358. Op amp IC9b is an inverting amplifier stage with negative feedback adjusted via pot VR1, so that its gain can be varied between 11.5 and 235 times to set the input sensitivity. D G S A K The preamp output is then fed directly to IC9a, which is configured as a comparator to ‘square up’ the audio signal and convert it into a train of pulses. The output of IC9a is then used to switch on transistor Q4, so that its collector voltage drops quickly to near-zero after the arrival of the audio signal. The collector of Q4 is connected via the 4.7nF coupling/ differentiating capacitor to pin 12 of gate IC7d, which is the inverter feeding trigger gate IC7c. External trigger input The EXT TRIG input comes in via CON4, which connects directly to the collector of Q4 via a 100Ω series resistor (the 1nF shunt capacitor across February 2009  67 6 5 4 IC6 3 2 4017B 8 S2 9 2 6 8 S1 0 7 4 4004 4040B 2.2k 680 IC2 PN200 A 10k 3 SCR1 C106D D9 Q1 10k READY LED1 K 100nF 1ms 2 6 4004 4004 4004 4093B 4.7k 1k 4148 4148 4148 D2 D3 1 5 3 IC8 100nF 10nF 10k 4.7k 100 10k 4093B 0 7 4 UNITS 8002 © 1 5 D1 Q3 BC338 10ms 100nF TPG S6 CLOCK UNITS 100nF TP2 POWER IC5 4017B IC4 4017B 100nF 100nF 100nF TPG 470 F 38kHz X1 9V BATTERY + S4 TP1 330k 2.2M 1 7 9 19020131 A PN200 D8 IC1 4069UB 0 LED2 TRIG’D CON3 + S3 100nF 100k 1k 4148 D4 K Q2 TENS 100 F EL BA M MAR G ORP YALED HSALF 8 470 S5 D6 IC11 4053B HUNDREDS ARM 4.7nF D5 + VR1 50k 2.2M 4.7k + 220k 22 F Q4 IC7 + 100nF 10M 22k Q5 BC338 1 F 110k D7 2N7000 10k 4148 10k SENSITIVITY 10k 470 CON2 R 10k 100 220k IC9 LM358 R 9 S T CON4 1nF 220nF IC10 4011B S T CON1 FLASH TRIGGER SHUTTER RELEASE IC3 4073B EXT TRIGGER CONTACTS ELECTRET MIC 27pF 27pF – Fig.3: component overlay for the Time Delay PhotoFlash Trigger, from the component side. The longest links can be made with tinned copper wire – we used insulated type to avoid shorts. CON4 is used for noise filtering, to prevent spurious triggering). Hence the collector circuit of Q4 effectively forms a ‘wired OR’ gate, as either Q4 or the external contacts can pull it down to ground and hence begin the triggering process. Cross-coupled gates IC10a and IC10b form control flipflop FF1, while gates IC7a and IC7b form control flopflop FF2. So pins 3 and 6 of IC10 is FF1’s Q output, controlling trigger gate IC7c, while pins 4 and 2 of IC7 are the Q output of FF2 and pins 3 and 5 are its Q-bar output. That’s why the ‘counter enable’ signal from pins 4 and 2 is taken back to pin 14 of IC4 (counter 1), as this is effectively the counter’s enable input. Similarly the ‘counter reset’ signal from pins 3 and 5 of FF2 is taken back to pin 15 of IC4, IC5 and IC6 – the MR pin for these devices. The NAND gate used to combine the count outputs from switches S1, S2 and S3 is formed by diodes D1-D3 plus IC8d (connected as an inverter) and the 10kΩ resistor connected between its pin 13 input and the +9V rail. This input of IC8d can therefore only rise to logic ‘high’ level when the cathodes of diodes D1, D2 and D3 are all high. This only occurs when 68  Silicon Chip the counter outputs selected by S1, S2 and S3 are all high at the same time. IC8d’s output at pin 11 then goes low. This pin is connected back to pin 13 of IC7d, which is the control flipflop’s R-bar input. The remaining circuitry at lower right of Fig.2 forms the pulse stretching and SCR driver block. Gates IC8a, IC8b and IC8c, together with diode D4 and the 1kΩ resistor/10nF capacitor combination form a one-shot monostable to stretch the very narrow ‘end of count’ pulse from IC8d. Transistor Q1 functions as a buffer to apply the stretched pulse to the gate of SCR1, to switch it on. When SCR1 conducts it triggers the electronic flash via diode bridge D6-D9 and the flash trigger output socket CON3. The complete circuit runs from a 9V alkaline battery, with S4 as the on/off switch. Unless you take a LOT of photos (or forget to turn the power switch off!), battery life should be very long indeed – probably approaching shelf life. Construction Virtually all of the circuitry and components used in the flash delay unit are mounted on a single PC board, coded 13102091 and measuring 185 x 102mm. The board has rounded cutouts in each corner so that it fits snugly inside a standard UB2 size jiffy box, measuring 197 x 113 x 63mm. The shafts of switches S1-S3 protrude through the box lid (which becomes the front panel) along with the power switch S4 and the two indicator LEDs. The battery fits inside the box underneath the PC board assembly, while all four input/output connectors are accessed via holes in the upper rear of the box itself. A small hole top left of the front panel allows screwdriver access to the sensitivity pot underneath. This should rarely need adjustment after the first time. Incidentally, we specify 3.5mm stereo sockets only because mono PC board-mounting types are virtually impossible to obtain. We obviously only use them as mono (ie, the “ring” terminal is left unconnected). Mono line plugs can of course be used – these are commonly available. The PC board overlay diagram of Fig.3 shows where all of the components are placed. Follow this diagram and the internal photo carefully, to build up the project without any problems. siliconchip.com.au The matching photograph (to the component overlay) also shows all component placement. We used DIL sockets for the ICs – they're cheap enough and make both assembly and any later troubleshooting much simpler! Parts List – Time Delay PhotoFlash Trigger 1 1 3 2 1 1 2 2 5 5 1 9 1 6 6 7 1 PC board, code 13102091, 186 x 102mm UB2 size jiffy box (197 x 113 x 63mm) 1 pole 12 position rotary switches (S1-S3) Mini SPDT toggle switches (S4,S6) Mini pushbutton switch, momentary NO (S5) 38kHz quartz 'watch' crystal (X1) 3.5mm stereo sockets, PC board mtg (CON1,CON4) 2.5mm concentric DC connectors (CON2,CON3) 14-pin DIL sockets, PC board mtg 16-pin DIL sockets, PC board mtg 8-pin DIL socket, PC board mtg 1mm PC board terminal pins 9V battery clip lead 25mm long M3 tapped spacers 6mm long M3 screws, countersink head 6mm long M3 screws, pan head M3 hex nut Semiconductors 1 4069UB hex inverter (IC1) 1 4040B binary counter (IC2) 1 4073B triple AND gate(IC3) 3 4017B decade counter (IC4-IC6) 2 4093B quad Schmitt NAND (IC7,IC8) 1 LM358 dual op amp (IC9) 1 4011B quad NAND (IC10) 1 4053B triple SPDT switch (IC11) siliconchip.com.au 2 2 1 1 1 1 5 4 BC338 (Q1,Q4) PN200 (Q2,Q3) 2N7000 (Q5) C106D SCR (SCR1) 5mm LED, green (LED1) 5mm LED, red (LED2) 1N4148 diodes(D1-D5) 1N4004 power diodes (D6-D9) Capacitors 1 470μF 16V RB electrolytic 1 100μF 16V RB electrolytic 1 22μF 25V tag tantalum 1 1μF 35V tag tantalum 1 220nF MKT metallised polyester 1 100nF MKT metallised polyester 8 100nF multilayer monolithic 1 10nF MKT metallised polyester 1 4.7nF MKT metallised polyester 1 1nF MKT metallised polyester 2 27pF NPO disc ceramic Resistors (0.25W 1% unless specified) 1 10MΩ 2 2.2MΩ 1 330kΩ 1 110k 1 100k 8 10kΩ 2 2.2kΩ 2 1kΩ 1 680Ω 1 100Ω 1 50kΩ potentiometer (VR1) 2 220kΩ 3 4.7kΩ 1 470Ω February 2009  69 Fully assembled and ready to place in the UB2 box (drilling detail at right). The front panel has holes for the six switches and two LEDs, along with the six screw holes which hold the panel to the threaded standoffs. We covered these with the front panel in the final version. Here is the suggested order for assembling the board: 1. Fit the four input/output connectors along the rear edge of the board. 2. Then fit the various wire links. There are 13 of these in all, eight of which are 0.4 inches long and can easily be made from resistor lead offcuts. The remaining five are somewhat longer, and will need to be made from lengths of tinned copper wire (pulled straight so there is no risk of them touching another link or component). 3. After the links fit the six terminal pins. Four of these are mounted in the usual from-the-top fashion, for the two test points (TP1, TP2) and their accompanying ground pins. The remaining two pins are used for the battery clip lead terminations, just to the right of the mounting position for S4 (at lower right). These pins are mounted from under the board, so there is plenty of pin left under the board for soldering the ends of the clip lead wires. 4. Now fit the IC sockets, making sure that you fit each one with the orientation shown in the overlay diagram so they guide you later in plugging in the ICs correctly. Note that a socket is not used for RLY1, because this is best soldered directly into the board. 5. Next fit the four three-pin SIL headers used for LK1-LK3. 6. After these fit all of the fixed resistors. These are not polarised, but make sure you fit each one in its correct position using the overlay diagram as a guide. If necessary use your multimeter/DMM to confirm the values before soldering them in position. 7. Next fit trimpot VR1. The board has holes to allow you to use either standard size of horizontal trimpot, so whichever kind you use there shouldn’t be a problem. 8. Now fit the smaller disc ceramic and multilayer monolithic ceramic capacitors, which are again not polarised. 9. Follow these with the electrolytic caps. There are only three of these (counting the 22μF tantalum unit), but they are polarised so watch their orientation. 10. Now you can fit the diodes, which are again all polarised. Take care here also to fit the 1N4148 ‘signal’ diodes in positions D1-D4, and the 1N4004 ‘power’ diodes in positions D5-D9. 11. After the diodes fit the four transistors, again watching their orientation but in this case also making Resistor Colour Codes o o o o o o o o o o o o o No.   1   2   1   2   1   1   8   3   2   2   1   1   1 70  Silicon Chip Value 10MΩ 2.2MΩ 330kΩ 220kΩ 110kΩ 100kΩ 10kΩ 4.7kΩ 2.2kΩ 1kΩ 680Ω 470Ω 100Ω 4-Band Code (1%) brown black blue brown red red green brown orange orange yellow brown red red yellow brown brown brown yellow brown brown black yellow brown brown black orange brown yellow violet red brown red red red brown brown black red brown red red brown brown yellow violet brown brown brown black brown brown 5-Band Code (1%) brown black black green brown red red black yellow brown orange orange black orange brown red red black orange brown brown brown black orange brown brown black black orange brown brown black black red brown yellow violet black brown brown red red black brown brown brown black black brown brown red red black black brown yellow violet black black brown brown black black black brown siliconchip.com.au E C 17.5 40.5 60.75 80 C D 38.0 E (ALL DIMENSIONS IN MILLIMETRES) 18.0 A 44.5 BOX LID/FRONT PANEL B 20.25 B B 40.5 13 F 80 HOLES C: 6.0mm DIAMETER HOLES E: 3mm DIAMETER CSK HOLES D: 5.0mm DIAMETER HOLE F: 12.0mm DIAMETER Value 220nF 100nF 10nF 4.7nF 1nF 27pF μF Code 0.22μF 0.1μF 0.01μF .0047μF .001μF NA siliconchip.com.au IEC Code 220n 100n 10n 4n7 1n0 27p EIA Code 224 104 103 472 102 27 E 45.75 45.75 E HOLES A: 9.0mm DIAMETER HOLES B: 7.0mm DIAMETER A 44.5 21.5 A 19.0 CL E E 19.0 20.25 A B D UPPER/REAR SIDE OF BOX (INVERTED) Fig.4: drilling detail for the UB2 Jiffy Box which houses the unit. CL Capacitor Codes sure that you fit the BC338 transistors in positions Q1 and Q4, while the PN200 transistors go in positions Q2 and Q3. 12. Now fit the 38kHz crystal X1. This is very small, so handle it carefully to avoid damaging it. Both of its leads are cranked outwards slightly and bent down by 90° about 3mm from the case, so that the crystal can lay on the top of the board with its leads passing down through the matching board holes. When the leads are soldered to their pads underneath, bend a resistor lead offcut into a ‘U’ shape and slip it down over the crystal case, with its ends passing down through the two additional holes. The ends can then be soldered to the copper underneath February 2009  71 so that the wire ‘U’ will act as a holddown. 13. Next fit the three rotary switches S1-S3, after cutting each of their spindles to a length of 18mm and smoothing off any burrs with a small file. These switches fit directly into the board but will only fit in with one orientation. This is where the single rotor 72  Silicon Chip pin is in the ‘three o’clock’ position. Note that when you have fitted the switches and soldered all of their pins to the pads underneath, it’s a good idea to program each switch to have a range of 10 positions. To do this, unscrew the nut from the threaded ferrule and then remove both the star lockwasher and the indexing DELAY TIME (UNITS = 10ms OR 1ms) www.siliconchip.com.au SILICON CHIP TENS HUNDREDS 0 DELAY TIME (UNITS = 1ms OR 10ms) 9 0 1 8 1 9 2 7 2 6 5 4 3 TIME DELAY PHOTOFLASH TRIGGER POWER UNITS 0 1 8 2 7 6 5 4 3 PRESS TO ARM ELECTRET SENSITIVITY DELAY UNITS 10ms 5 4 3 TRIGGERED 6 9 8 7 1ms READY DELAYED FLASH TRIGGER OUT CAMERA SHUTTER RELEASE EXTERNAL TRIGGER CONTACTS (NO) ELECTRET MICROPHONE INPUT Fig. 5: same-size front panel artwork which can be photocopied or downloaded from siliconchip.com.au. stop washer. Then after turning the spindle anticlockwise as far as it will go, replace the stop washer with its cranked indexing pin passing down into the rectangular hole between the numbers ‘10’ and ‘11’ moulded into the plastic. After this, place the lockwasher over the indexing washer, and finally screw on the nut again to hold it all together. You’ll find that once this is done each switch will have only 10 positions. 14. Now fit the SCR, which mounts flat against the top of the board with its ‘metal plate’ side uppermost. The three leads of the device are bent down by 90° 6mm away from body and the outer leads cranked slightly outwards, so all three will pass easily down through the holes in the board. Then after the leads have been soldered to the pads underneath, the SCR is held down to the board using an M3 x 6mm screw and nut. 15. Fit the reed relay RLY1, orientated as shown in the overlay diagram. Note that although the relay has the same ‘footprint’ as a 14-pin DIL IC, it has only eight pins – four at each end. These pins should all be soldered to the pads underneath, to hold the relay firmly in place. 16. Next fit the two LEDs, remembering that LED1 is the green LED and LED2 is the red LED. Both should be fitted with their cathode (‘flat’) side towards the top of the board, with the leads left straight and measuring about 18-19mm between the bottom of the LED body and the top of the board. 17. The final wiring steps are to solder the ends of the battery clip lead wires to the terminal pins under the board (making sure you connect the red positive lead to the upper ‘+’ pin), and then fit power switch S4 just to the left of these pins. Note that this switch does not mount directly on the board, but via three short lengths of hookup or tinned copper wire so that the switch itself can be mounted to the box lid/front panel. For the moment though, just solder the three wires to the lugs on the rear of the switch, and solder the ends of the wires to the pads under the board. The wires should each be about 12mm long. 18. Your board assembly should now be complete, apart from plugging the various ICs into their sockets. So do this now, making sure that you plug each one into its correct position siliconchip.com.au and with the correct orientation. Checkout time Your flash delay unit board should now be ready for a quick functional checkout. To do this, first connect switches S4, S5 and S6 to the board using short lengths (say 25mm) of hookup wire.Then set clock switch S6 to the 10ms position, set the three rotary switches S3-S2-S1 to a setting of say ‘500’ and connect the clip lead to a suitable 9V alkaline battery . Then turn on power switch S4. You should find that the red ‘triggered’ LED glows briefly but then goes dark and the green ‘ready’ LED1 begins glowing. If you have access to an oscilloscope or a frequency counter, you can check that the board’s clock oscillator is working correctly by checking the signal at test point TP1. You should find a 38kHz square wave of around 9V peak-to-peak. You can also check the timing pulses at TP2, which should have a frequency of 100Hz if you have switched S6 to the ‘10ms delay steps’ option. If you switch S6 to the ‘1ms steps’ option the frequency should change to 1kHz. If all seems well so far, try plugging a 3.5mm jack plug into CON4 and then shorting its ‘tip’ and ‘sleeve’ connection lugs together with a short length of wire. You should find that nothing happens when you first do this, because the control circuit has not been ‘armed’. But if you now press S5 briefly and try again, this time LED1 should turn off and LED2 turn on, indicating that the circuit has been triggered. And it should remain in this state for five seconds, if you have set S3-S1 for ‘500’ and S6 for 10ms (500 x 10ms = 5000ms or 5s). At the end of this time it should switch itself back to the ‘ready’ state, with LED2 dark and LED1 glowing again. Assuming this is what you find, your delay unit is almost certainly working correctly. So switch off the power, because you should now be ready for the final assembly step: fitting the board assembly into the box. Final assembly Before you can fit the unit into its box, you may need to drill the various holes in the box first – unless you are building it from a kit with a prepunched box and lid. There are not many holes to drill as siliconchip.com.au Making a custom microphone If you want to make use of the delay unit’s sound triggering option, you’ll need to make up a custom microphone lead. This is very straightforward, as you can see from the diagram below. The only components involved are a 3.5mm mono or stereo plug, a suitable length of screened single-core microphone cable and a small electret microphone insert. At the microphone insert end of the cable, just make sure that the screening braid connects to the ‘earthy’ pin or pad of the insert – i.e., the one which is clearly connected to the metal case of the insert. The cable’s inner wire connects to the other pin or pad. At the other end, the centre wire connects to the plug’s ‘tip’ connection lug, while the screening braid connects to the ‘sleeve’ lug (the one which connects to the body of the plug). ELECTRET MICROPHONE INSERT SCREEN BRAID CONNECTS TO INSERT CASE Needless to say making up a cable for the delay unit’s ‘contact closure’ input is even simpler. Here all you need is a 3.5mm mono or stereo plug plus a suitable length of screened cable, connected to the plug in exactly the same way as with the microphone. At the other end the inner wire and screening braid are simply connected to the two contacts (normally open) of the sensor unit you’re using to provide your ‘triggering event’. Parts required 1 miniature electret microphone insert 1 3.5mm mono or stereo line plug Suitable length shielded microphone cable ACTIVE WIRE CONNECTS TO 'TIP' LUG SUITABLE LENGTH OF SCREENED MIC CABLE you can see from the drilling diagram, so preparing the box and its lid won’t take very long. If you are building the unit up ‘from scratch’ rather than from a kit, you may also want to fit the lid with a copy of the front panel artwork. This can be photocopied onto an A4 size adhesive label, and then cut to size before peeling off the backing and sticking it to the lid. To protect it from dirt and ‘finger grease’ you can then cover it with some clear adhesive film or, as we often do, laminate it (A4 laminators and sleeves are now ridiculously cheap!). The board assembly mounts on the underside of the box lid via six M3 x 25mm tapped spacers, using countersink-head M3 screws to attach the spacers to the lid and pan-head screws to attach the board to the spacers. Just before you screw everything together, though, you need to mount switches S4, S5 and S6 in their respective positions on the lid/front panel, and also fit the lugs of each switch with a 25mm length of tinned copper wire. These will pass down through the matching holes in the board when 3.5mm STEREO PLUG SCREEN BRAID CONNECTS TO 'SLEEVE' LUG it’s brought up to the spacers, and are soldered to the pads underneath. Note that pushbutton switch S5 (the “arm” switch mounts through the front panel from above, secured by a nut underneath the panel, while S4 and S6 mount through the panel from below and are secured with nuts from above. When you are attaching the board to the lid/front panel via the spacers, take care to ensure that the tops of the two LEDs protrude through their matching holes, as do the rotary switch and pot spindles through their own holes. Needless to say you also have to ensure that the wires from the lid-mounted switches pass down through their own holes in the board. This is a bit fiddly but not difficult if you take it slowly. All four of the input/output connectors CON1-CON4 are accessed through holes in the rear side of the box itself, with identification labels along the top of the front panel. As noted before, the unit’s battery simply sits in the bottom of the box, held in place by either a small bracket fashioned from sheet aluminium or even secured with a length of ‘gaffer’ tape. SC February 2009  73