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Notes & Errata 6-Digit Retro Nixie Clock Mk2, February-March 2015: the articles stated that GPS modules with RS-232 output levels were not suitable for use. However, we have now managed to incorporate support for such modules into the final software. Note that a resistor of around 4.7-10kΩ must be placed in series with the GPS module’s TX line (ie, the wire to pin 3 of CON7, marked “TX” on the PCB) to avoid damaging the microcontroller. The micro will auto-detect inversion state and baud rate (4800 or 9600). Ask SILICON CHIP . . . continued from page 95 the LEDs then each flashing once in sequence. Continue to hold the Clear All/Program switch when you need to disable an indicator and press its corresponding Clear/Prgm button as detailed in step 2. Note that there is not just a single Clear/Prgm button but one associated with each indicator LED. In other words, the Clear/Prgm buttons are located with each LED and are used to enable or disable an indicator LED. The Clear All/Program switch, when briefly pressed for under 6s, is used to clear the flashing “bin-out” LEDs once you put these bins out for collection. There are no software updates for this design. 1.5V power supply wanted I have a voltage sensitive transmitter Note also that there is no pull-up resistor on the MCLR pin (pin 1) of IC1; while the data sheet suggests one may be necessary, we have found it works fine without. If you want to add one, it can be soldered between pins 1 & 2 of CON3. Currawong 2 x 10W Stereo Valve Amplifier (November 2014-January 2015): in the November 2014 issue on page 32, circuit diagram Fig.2 shows T1’s secondary voltages incorrectly. The two bottom windings should be shown as 15VAC, not 37VAC. that is powered by a single AA battery. As the battery ages the transmitter becomes unstable. I want to use the Tx in my car and run it from the vehicle battery. Have you ever produced a stable 12V to 1.5V supply that I could use? I have been looking at a simple circuit using a voltage regulator but find that voltage regulators only go down to 5V. The required current consumption is negligible. (K. J., via email). • You can use an LM317 to provide a 1.25V supply directly or slightly increase this using a couple of resistors. The Adjust-to-Out terminal resistor value should be 120Ω or 100Ω to ensure sufficient minimum current for the regulator. Alternatively, a shunt regulator consisting of a resistor connected in series with three 1N4148 or 1N4004 diodes across the 12V rail will give a nominal 1.5V supply across the diodes. If the transmitter’s current drain is minimal (less than 5mA), then a 1kΩ 0.5W resisSC tor can be used. 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IBC National Instruments...................... 6 Oatley Electronics........................ 87 Ocean Controls.............................. 6 Qualieco....................................... 55 Questronix.................................... 95 Rockby Electronics....................... 77 Rolec OKW................................. 7,9 Sesame Electronics..................... 95 Silicon Chip Binders..................... 39 Silicon Chip PCBs........................ 95 Silvertone Electronics.................. 41 Tronixlabs..................................... 95 Virtins Technology.......................... 8 Wiltronics........................................ 4 Worldwide Elect. Components..... 95 X-ON Electronic Services............ 95 WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. 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