Battery Eliminator Problem - Electronic Circuits Projects Diagrams Free

pixnum · 13th December 2006, 12:40 PM

Dear Friends,

I have a problem regarding battery eliminator at output stage. When I connect my audio amp with it, the voltage is getting zero at input stage of voltage of amp and there is no sound. All though audio amp is working good with other eliminator. But when I check the output voltage of eliminator it shows me right voltage like 8v. As I am giving you my component details as follows:

Transformer = 12-0-12 Step Down Centre Tap
Diode = IN 4007 (2 pieces for bridge)
Capacitor = 4700uf 50v (1 piece)
Resistance = 100K/3W POT(1 piece)
Max Voltage = 17v

Now do you solve my problem if you can !

Thank you !

**Nigel Goodwin** · 13th December 2006, 01:03 PM

What's the 100K pot for?.

You also need four diodes for a bridge, you have two which could make a fullwave rectifier in conjunction with your centre tapped transformer.

evandude · 13th December 2006, 02:55 PM

I assume you are trying to use the 100k pot in place of an actual voltage regulator? Not only would that do an extremely poor job of regulating the voltage, you also end up with a very high-impedance source which is probably a terrible choice for powering an amplifier.

pixnum · 13th December 2006, 04:04 PM

Thank you Nigel Goodwin & Evandue !

100K POT means Potentiometer !
Please tell me how to reduce high impedence source !
With this eliminator I want to run mp3 player, FM Receiver.etc. Actually I don't want to use actual voltage regulator instead I like to use 100k pot in this regard.

Please give me some light in this regard !

**Nigel Goodwin** · 13th December 2006, 05:25 PM

Quote:

Originally Posted by pixnum

Thank you Nigel Goodwin & Evandue !

100K POT means Potentiometer !
Please tell me how to reduce high impedence source !
With this eliminator I want to run mp3 player, FM Receiver.etc. Actually I don't want to use actual voltage regulator instead I like to use 100k pot in this regard.

We know what it means, but it's completely useless for what you want.

You NEED a regulator!.

audioguru · 13th December 2006, 06:40 PM

Adjust the resistance of the pot to half so it is 50k ohms. Then the max load current when its output voltage is 8V is only (17V-8V)/50k= 0.18mA. Nearly nothing.

evandude · 13th December 2006, 08:16 PM

Quote:

Originally Posted by pixnum

Please tell me how to reduce high impedence source !
With this eliminator I want to run mp3 player, FM Receiver.etc. Actually I don't want to use actual voltage regulator instead I like to use 100k pot in this regard.

If you want variable voltage output adjustable by a potentiometer, use a variable regulator like the LM317. If you keep using a pot by itself then you can expect it to keep not working.

Odysseas · 13th December 2006, 08:29 PM

I am forced to agree

. If you use a pot for your application, it will turn into smoke before you can blink an eye. LM317 is surely one option, but I hear that it would also be possible to build a switching regulator with an adjustable voltage output. Perhaps someone knows more about that?

You could reduce the impedance by using several potentiometers in parallel. A stereo potentiometer would reduce the impedance by half, but it would still be useless.

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13th December 2006, 12:40 PM	(permalink)
pixnum	Battery Eliminator Problem Dear Friends, I have a problem regarding battery eliminator at output stage. When I connect my audio amp with it, the voltage is getting zero at input stage of voltage of amp and there is no sound. All though audio amp is working good with other eliminator. But when I check the output voltage of eliminator it shows me right voltage like 8v. As I am giving you my component details as follows: Transformer = 12-0-12 Step Down Centre Tap Diode = IN 4007 (2 pieces for bridge) Capacitor = 4700uf 50v (1 piece) Resistance = 100K/3W POT(1 piece) Max Voltage = 17v Now do you solve my problem if you can ! Thank you !

13th December 2006, 01:03 PM	(permalink)
Nigel Goodwin	What's the 100K pot for?. You also need four diodes for a bridge, you have two which could make a fullwave rectifier in conjunction with your centre tapped transformer. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

13th December 2006, 02:55 PM	(permalink)
evandude	I assume you are trying to use the 100k pot in place of an actual voltage regulator? Not only would that do an extremely poor job of regulating the voltage, you also end up with a very high-impedance source which is probably a terrible choice for powering an amplifier. __________________ EEgeek.net

13th December 2006, 04:04 PM	(permalink)
pixnum	Thank you Nigel Goodwin & Evandue ! 100K POT means Potentiometer ! Please tell me how to reduce high impedence source ! With this eliminator I want to run mp3 player, FM Receiver.etc. Actually I don't want to use actual voltage regulator instead I like to use 100k pot in this regard. Please give me some light in this regard !

13th December 2006, 06:40 PM	(permalink)
audioguru	Adjust the resistance of the pot to half so it is 50k ohms. Then the max load current when its output voltage is 8V is only (17V-8V)/50k= 0.18mA. Nearly nothing. __________________ Uncle $crooge

13th December 2006, 08:29 PM	(permalink)
Odysseas	I am forced to agree . If you use a pot for your application, it will turn into smoke before you can blink an eye. LM317 is surely one option, but I hear that it would also be possible to build a switching regulator with an adjustable voltage output. Perhaps someone knows more about that? You could reduce the impedance by using several potentiometers in parallel. A stereo potentiometer would reduce the impedance by half, but it would still be useless. __________________ Seize the time, and seize it now!