Alternative usage for LM3875

Tekko · 22nd January 2005, 09:11 PM

Hello! I was sitting here half bored until i came up with a idea, why not try to use them as a VSD (Variable Speed Drive) So i took a big transformer and hooked a secondary to the speaker outs on the 3875´s and the 230 primary to a fan and a motor. This is the result: http://hififorum.knaak.dk/Tekko/lm3875/ <-- 125Hz on the fas and over 600Hz on the motor using a function generator on the computer and the cassette deck as preamp. There is sound on both videos.

Bas Horneman · 22nd January 2005, 10:45 PM

Hi Tekko,

Could you not pump those AVI's into some encoder and make it wmv or something...this way it takes 10 minites to download!

Cheers,
Bas

I converted your Video7.avi to video7.wmv from 27mb to 2 mb...quality of the wmw is lower ofcourse

http://basenjes.de/video7.wmv

DigitalJunkie · 23rd January 2005, 01:53 AM

I had an idea about using a +12V audio amp chip (TDA7350,or many others.) as a driver for a small 12V-120/240Vac inverter.Add another chip with a nice 50/60hz sine wave,and suitable power trannie(wired "backwards" for step-up)and you're set.Doesn't seem too complicated.Add a couple pots to set the freq and level (voltage out),maybe replace them with fixed reistors after you get it all dialed in.
You wouldn't be able to get a whole lot of power,maybe 25W? (unless you could parallel the chips?) but it might be handy for recharging phones,pda's,laptops?,running a small CFL light,etc from 12V sources.
But one bonus is that it has a sinewave output,none of that "modified squarewave" stuff.

soundNERD · 23rd January 2005, 01:57 AM

DigitalJunkie,

read this:

OP-AMP based car amp power supply

I had asked the same question before.

Tekko · 23rd January 2005, 08:55 AM

This is controlled via the computers soundcard and a function generator. I could encode them but i don´t have a encoder.

22nd January 2005, 09:11 PM	#1
Tekko diyAudio Member Join Date: Jan 2005	Alternative usage for LM3875 Hello! I was sitting here half bored until i came up with a idea, why not try to use them as a VSD (Variable Speed Drive) So i took a big transformer and hooked a secondary to the speaker outs on the 3875´s and the 230 primary to a fan and a motor. This is the result: http://hififorum.knaak.dk/Tekko/lm3875/ <-- 125Hz on the fas and over 600Hz on the motor using a function generator on the computer and the cassette deck as preamp. There is sound on both videos.

22nd January 2005, 10:45 PM	#2
Bas Horneman diyAudio Moderator Emeritus Join Date: Apr 2002 Location: The Netherlands Blog Entries: 18	Hi Tekko, Could you not pump those AVI's into some encoder and make it wmv or something...this way it takes 10 minites to download! Cheers, Bas I converted your Video7.avi to video7.wmv from 27mb to 2 mb...quality of the wmw is lower ofcourse http://basenjes.de/video7.wmv __________________ Boatanchor amps forum My "adventures" in audio

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23rd January 2005, 01:53 AM	#3
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	I had an idea about using a +12V audio amp chip (TDA7350,or many others.) as a driver for a small 12V-120/240Vac inverter.Add another chip with a nice 50/60hz sine wave,and suitable power trannie(wired "backwards" for step-up)and you're set.Doesn't seem too complicated.Add a couple pots to set the freq and level (voltage out),maybe replace them with fixed reistors after you get it all dialed in. You wouldn't be able to get a whole lot of power,maybe 25W? (unless you could parallel the chips?) but it might be handy for recharging phones,pda's,laptops?,running a small CFL light,etc from 12V sources. But one bonus is that it has a sinewave output,none of that "modified squarewave" stuff.

23rd January 2005, 01:57 AM	#4
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	DigitalJunkie, read this: OP-AMP based car amp power supply I had asked the same question before.

23rd January 2005, 08:55 AM	#5
Tekko diyAudio Member Join Date: Jan 2005	This is controlled via the computers soundcard and a function generator. I could encode them but i don´t have a encoder.

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