DC-DC converter 2

Published:2013/7/9 3:10:00 Author:muriel | Keyword: DC-DC converter | From:SeekIC

This DC-DC converter ( inverter ) needs nothing but unmodified Radio Shack parts. You don't need to build or wind any coils or transformers. This is a cheap-and-dirty experimenter's circuit. I tested this and it worked for me, but I disclaim all warranties! | | NOTE: --+-- is connected, --|-- is not connected. | | NOTE: Some IC connections not shown, see below. IC connections not shown:Pin 1 of all 555's goes to ground.Pins 4 and 8 of all 555's go to +12 volts DC. It is recommended to have apower supply bypass capacitor of at least .1 uF from Pin 8 to ground on each 555.Pin 5 of all 555's goes to ground through a capacitor of .01 to .1 uF.Pin 7 of all 555's is left unconnected.Pin 14 of the 4013 gets connected to +12 volts DC.Pins 4, 6, 7, 8, 9, 10, and 11 of the 4013 get connected to ground.Pins 12 and 13 of the 4013 are left unconnected.Notes:R1 and R2 are each parallel pairs of 150 ohm, 1/2 watt. (Otherwise, use75 ohm 1 watt, not available at Radio Shack.)D1 and D2 are any type rectifier diode rated at least 1 amp and 600 volts.C1 and C2 are 1 uF 250 VDC, such as Radio Shack 272-1055. Should you getthe 200 volt version, the inverter will still work but reliability will beslightly compromised, since the voltage on these capacitors will likelyslightly exceed 200 volts.T1 is a 12 volt center-tap, 3 amp transformer, such as Radio Shack 273-1511.This transformer is used as a step-up transformer and will put out approx.200 volts square wave AC.It is recommended to parallel the transistors with zener diode pairs. Putthree 12 volt 1 watt zener diodes in series, all three in the same direction.Put one of these triplets from collector to base of each TIP3055 transistor,with the cathode end towards the collector. These zener diode banks areshown as Z1 and Z2.The transistors must be appropriately heat-sinked. The Radio Shack 276-1363heat sink is adequate for one transistor if heatsink grease is used and theheatsinks are not enclosed in a small, poorly ventillated space. It is notnecessary to use any heatsink insulators if the heatsinks will not beconnected nor shorting to anything.DANGER: This circuit has high voltage capable of causing fatal electric shock.Do anything described here only at your own risk.This inverter will charge up capacitors to approx. 400 volts or slightly more. Therefore, it is recommended to use energy storage capacitors rated at least for 400 and preferably for 450 volts. For some ideas for flashtubes and capacitors suitable for larger strobes and rated for these voltages, go to my Large Xenon Strobe Parts Page. You can use the usual 330 or 350 volt capacitors if you can ensure that flashing will occur and reliably discharge the capacitor before the voltage builds up to an excessive level, or if you add circuitry to disable this circuit should flashing fail to keep the energy storage capacitor's voltage from building up past its rating. Alternatively, you can use an 18 volt centertap transformer, to get a maximum output voltage slightly under 300 volts. You will have to double C1 and C2 to get similar power output. Another alternative is to use a lower power transformer and reduce C1 and C2 for a lower power output. With an energy storage capacitor capable of withstanding 450 volts and stored energy not exceeding 6 joules (60 uF at 450V or 76 uf at 400V), the Radio Shack flashtube will operate safely if it is flashed infrequently enough to not get an average power input of more than 6 watts. (1 flash per second with the 6 joule limit.)



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