Tip & How-To about Radio Communications

Building Power Supplies

Get you a 12 to 15 volt Transformer. Buy two big power diodes from Radio Shack. A capacitor 100uf to 470uf that handles 16 volt or 20 v. Buy two 0.01uf Disc capacitors. Get you a board 6x6 inches. Bolt down transformer to board. Hook leads to Diode like this: One lead to Striped side of Diode(1). the other lead to Diode(2) opposite side. Use capacitor 470uf (+) to striped side of Diode(2). Use capacitor(-) to Black side of Diode(1). Make sure polarity is right + - etc..Solder 0.01uf capacitor across Diode(1) and Solder other 0.01 uf Capacitor across Diode(2). Parallel wise. This Bypasses Rf so you get no Hum. There you go simple 12 Volt DC current to run mobile radios indoors.

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how can i build a power supply s-0217d

You can build a similar powersupply using voltage regulators.
LM78M18,LM7818 78 for positive voltage(79 for negative) and the last two=regulated voltage.
connect them to the same transformer 18+2V(drop)=20VDC or > 14.2vAC.
So you will need
1:14.5vAC -18vAC transformer
2:Bridge rectifier or 4 diodes (schottky for efficiency)
3.The voltage regulators.
4.2 electrolytic 100uf-470uf capacitors per Vreg
5. one 100nf capacitor after each VReg in parallel with electrolytic.

Oct 24, 2014 | Audio Players & Recorders

1 Answer

i have a samsung 920n and the power light just keeps flashing green when i switch on and there is an intermittent clicking noise every 2 to 3 seconds.. i replaced all caps (one 470uf was damaged) exce

Are you sure that you used the correct type of capacitors in the repair? They need to be low ESR, High Temp and High ripple current. Capacitors from places like Radio Shack or FRYs will not work because they are only general purpose and the switching power supply can not work right with them installed and they could even damage the electronics on the board. Here is some more information on getting the right capacitors.


Jun 13, 2012 | Samsung Computers & Internet

1 Answer

my midland 1001z has power to it but all it does is give a humming sound!The mic. will key up and the tx light comes on but when I release the mic. the humming sound gets louder,is the unit screwed? thks K.P.

If you are using a power supply. Get you a better power supply(full filtered) RADIO SHACK has many 12 volt 3 amp models. Run power wires away from radio about 10 feet away to eliminate hum. AM does hum when its near power lines, household appliances. Keep it away from TV's etc. Turn off TV then listen to it. Make sure you have good outdoor antenna like Antron A99 18ft. Fiberglass on Tv pole or Tower. If its inside car --its the engine. you need a Radio Shack Power filter. A coil of wire wrapped around a core and big capacitor on the (+) side shunted to ground by a 470uf Capacitor. Turn off engine then listen.

Apr 04, 2011 | Midland 1001Z 40-Channels Base CB Radio

5 Answers

Can changing 3 capacitors on motherboard solve my problem?

We had a power surge and my VL2018W LCD monitor stopped working... blank screen and flashing blue light.

I carefully opened up the back and found the power board (the one the AC plug goes into). There were about 5 electrolytic capacitors that were bulging (but not ruptured). There were 3 with the values listed by the original poster (470uF @ 25V) and 2 with 1000uF @ 10V.

I scrounged a couple of 2200uF@10V caps for the last two and bought 3 470uF @ 35V caps from Radio Shack (P/N 272-1030).

Luckily, the monitor came right back up and seems to be OK. It was out of warranty, so there wasn't a big risk.

Just increasing the working voltage won't do that much for you. If any caps are bad, just replacing them with the same value is good enough, but a higher working voltage won't hurt (usually means a bigger cap).

Good luck.


May 04, 2008 | Princeton Digital VL2018W Monitor

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