Transformerless Power Supply CircuitIf you are not accomplished in ambidextrous with it, again leave this activity alone.Although Mains accessories can itself absorb a lot of current, the circuits we body to ascendancy it, usually alone crave a few milliamps. Yet the low voltage ability accumulation is frequently the better allotment of the architecture and a abundant allocation of the cost.
This ambit will accumulation up to about 20ma at 12 volts. It uses capacitive reactance instead of resistance; and it doesn't accomplish actual abundant heat.The ambit draws about 30ma AC. Always use a agglutinate and/or a aqueous resistor to be on the safe side. The ethics accustomed are alone a guide. There should be added than abundant ability accessible for timers, ablaze operated switches, temperature controllers etc, provided that you use an optical isolator as your circuit's achievement device. (E.g. MOC 3010/3020) If a broadcast is unavoidable, use one with a mains voltage braid and about-face the braid application the optical isolator.C1 should be of the 'suppressor type'; fabricated to be affiliated anon beyond the admission Mains Supply. They are about covered with the logos of several altered Safety Standards Authorities. If you charge added current, use a beyond amount capacitor; or put two in parallel; but be accurate of what you are accomplishing to the Watts. The low voltage 'AC' is supplied by ZD1 and ZD2.
The arch rectifier can be any of the baby 'Round', 'In-line', or 'DIL' types; or you could use four abstracted diodes. If you appetite to, you can adapt R2 and ZD3 with a 78 Series regulator. The abounding sized ones will work; but if amplitude is tight, there are some baby 100ma versions accessible in TO 92 blazon cases. They attending like a BC 547. It is additionally account acquainted that abounding baby circuits will assignment with an able supply. You can, of course, adapt any or all of the Zenner diodes in adjustment to aftermath a altered achievement voltage. As for the mains voltage, the advancement apropos the 110v adaptation is aloof that, a suggestion. I haven't congenital it, so be able to agreement a little.
