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Advertising Index Ask SILICON CHIP . . . continued from page 103 then adjusted for switch-on, again at 11.5V. Some trial and error is required for these adjustments using a variable power supply. If a variable supply is not available, use a 15V supply with a 10kΩ linear potentiometer across the supply. The wiper is then adjusted for the test voltages and applied to the signal voltage input on the Voltage Switch. We are planning to update this project next month, with a new PCB and a 30A relay. Simple digital 230VAC timer wanted I was wondering if you had created in the past a simple 230VAC count up/ count down timer. I want to be able to turn on a 230VAC device in X hours time, or turn off a device in X hours DOWNLOAD OUR CATALOG at www.iinet.net.au/~worcom WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au time, as set by a mode switch. Once triggered its state does not change until reset. I am looking for a device that has the following controls: (1) a button/ switch to set mode to count up/down; (2) a pushbutton to set the timer values, ie, +1 hour each time it’s pressed, to a maximum of 23 hours from now; (3) a simple 2-digit display showing the hours selected; (4) a start/reset button and (4) up to 10A capability, all in a nice compact box! I can’t find anything on the market that does it. Yes, you can buy programmable timers with lots of on/off programs but they are far too hard to Notes & Errata 1.5kW Induction Motor Speed Controller (April & May 2012): there is now a more rugged IGBT bridge with higher current ratings available as a drop-in replacement for the originally specified STGIPS20K60. The new device is the STGIP30C60 and it has a rating of 30A (up from 20A). The total power dissipation ratings are unchanged. We recommend that all new speed controllers now be constructed with the new device, as the upgrade will provide increased reliability. However, we do not recommend that readers use it with a motor or 104  Silicon Chip pump rated in excess of 1.5kW. In those cases where the speed controller will not reliably start a pool pump with the new IGBT bridge fitted, it will be possible to reduce the value of the specified shunt resistor from 15 milliohms to 12 milliohms to provide for more starting current. Dual Channel Audio Delay (November 2013), Stereo Echo & Reverberation Unit (February 2014): IC2 must be a WM8731. Do not use the specified alternative part (TLV320AIC23BIPW) as this has the function of two pins swapped (21 & 22). Altronics.........................loose insert Consulting & Eng. Services........ 103 Element14...................................... 5 Emona Instruments...................... 21 Enertel Pty Ltd............................. 11 Gless Audio................................ 103 Hare & Forbes.......................... OBC Icom Australia................................ 9 Jaycar .............................. IFC,49-56 KCS Trade Pty Led......................... 7 Keith Rippon .............................. 103 KitStop.......................................... 12 LD Electronics............................ 103 Master Instruments.................... 103 Microchip Technology................... 39 Mikroelektronika......................... IBC Ocean Controls............................ 15 QualiEco Circuits Pty Ltd............. 47 Quest Electronics....................... 103 Radio TV & Hobbies DVD............ 27 RF Modules................................ 104 Rohde & Schwarz.......................... 3 Sesame Electronics................... 103 Silicon Chip Binders..................... 69 Silicon Chip Online Shop........ 96-97 Silicon Chip Subscriptions........... 95 Television Replacements........... 103 Wiltronics...................................... 13 Worldwide Elect. Components... 104 use. I need something that I can use with almost a zero learning curve, ie, just plug the device in, set the timer, and forget. (N. M., via email). • We have published numerous timers but none that are as simple to use as you describe with just hour steps. Most of our timers have minutes and hours adjustments. You may be able to obtain a salvaged mains timer from a clothes dryer, heater or microwave oven. Some timers are electromechanical and use a mains synchronous motor to drive the timer. More basic ones use a clockwork timer and contact switch. Others are electronic and will require a low voltage power source instead. You then use the switching contacts to drive a relay that has changeover contacts. Depending on the contact arrangement, the timer can either switch on or switch off an appliance SC with the timer. siliconchip.com.au