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ostie01 13th March 2006 06:34 AM

optocoupler to eliminate ground loop
Hi, would like to know if it's possible to eliminate ground loop problem
with optocoupler or can it be used in amplifier input.Are they stable enough. Can I use this device to transfert analog signal like in audio circuit. Thanks everybody for your time.

Upupa Epops 13th March 2006 07:09 AM

Look at datasheets of CP Clare....

peranders 13th March 2006 07:49 AM

There are analog optocouplers but the quality isn't enough for audio I'm afraid. Check for instance IL300 from Vishay. I have used it in a 4-20mA loop and for this purpose it's OK.

davidsrsb 13th March 2006 07:52 AM

There are some instrumentation isolators that may be good enough for audio, using a pwm system across capacitors.

Linear modulation of an IR diode driving a PIN diode works fairly well except at very low frequencies where I have seen strange non linearity and memory effects.

A transformer may be your best solution.

peranders 13th March 2006 08:07 AM

Seriously, I think it better to solve the casue of the ground loop problem. Have you built the gear or is it bought?

ostie01 13th March 2006 08:54 AM

Hi, thanks for these great reply.Not built anything yet.It's for my 4way active crossover project.When I hook it up to a power amplifier, I got some hum in the speaker.Tried some tricks like disconnect ground from one end of interconnect but this is the worse I can do, more hum.tried some other interconnect with same result.

Just take a look at this link, this is my crossover project.Every cables is sheilded, separate transformer, each board has it's own filtering caps and voltage regulator. All capacitors are polystyrene or polypropylene for the bass output. all ICs are NE5532.Each ICs has a 22 Ohm resistor and a 22uF capacitor at the neg and positive input. Just let me know what you think. Thanks

The last pic is a picture of my 4way speaker that I've built.

All my power amp are Rotel exept for the 15 inches drivers this are power by an Harman Kardon citation 7.1 with 450 watts/channel.

My crossover is built in a Rotel power amplifier case that has been modified, reduce in height to match the height of my Rotel line conditionner.Still have to finish the front(sanding and painting to match other Rotel components.

richie00boy 13th March 2006 09:02 AM

I suspect that your problem lies in an issue with your grounds within your crossover. When you have separate regs for different boards it can become tricky to keep everything starred properly.

ostie01 13th March 2006 09:08 AM

HI, I know what you mean but the 2 boards have the same ground path.Each boards is grounded to the case.

ostie01 13th March 2006 09:15 AM

Here is my design for the 4way crossover, should sound great if everything is O.K.

richie00boy 13th March 2006 09:42 AM

If things are grounded to your case, have you used isolated input and output sockets? Also when you say grounded to the case, do you mean a star ground at ONE point on the case for ALL boards?

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