matching impedances

I always used a 10k resistor to a 5 K pot, and set the level from there. If it is here it can be tampered with, you might want to put an internal 100K pot, then set the level control to around 74% of the level you want with the internal pot. Also, don't bond the primary and secondary commons toothier to avoid a ground loop.

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Thanks Michael. I'm bringing a lot of spare parts to the job with me today and I'll let you know how it all works out. Best regards, Lenny.

You're welcome. I used to build those a couple at a time, to have extras in my truck. :)

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There are two kinds of people on this earth: The crazy, and the insane. The first sign of insanity is denying that you're crazy.

Michael I used two 10K resistors off the secondary of a 70.7V transformer. I felt that this would maintain a balanced line input to my amp. The primary was tied to the incoming 70V line and was tapped at 4W. The only balanced line inputs to the amp were mic 1 and mic 2. With the

10K resistors in series the level into the balanced mic input of the amp was perfect. The amplifier was a Bogen 60W unit. We added two more speakers to the system for a total of 4 all tapped at 4W. This is a commercial kitchen with the unbelievable noise level of a subway tunnel. Now they'll have no trouble hearing the pages. Thanks again for the advice. Another fire put out. Best regards, Lenny.

You're welcome. If that was a typical Bogen amp, the inputs are transformer isolated 150 or 600 ohm impedance.

Try putting in a system in a corrugated box plant sometime if you want noise! ;-) 35 watts covered the whole plant, except near the corrugators, and each had their own 100 watt amp, with PA horns six feet away from each operator.

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This is an interesting group I just had an impedance issue i got help with on a project that I am working on, in summary I used CO sensors in a parking garage the rating on the comunication bus is 2000ft, When I designed the project during estimation I took a risk to strech to 3000 based on the probability that the voltage drop would not migatate me. Anyhow to make a very long story short, it turned out between my low volatge sub and my inherient nature for taking small calculated risks, the com was 3500 ft, I tried to figure out the best end of the line terminator , going back to the impedance matching topic that sparked my interest, after calling some experts, I got the matched impedance, but still need to and another 50VA transformer.... lesson learned on my part

Thanks for sharing Allan J Federman snipped-for-privacy@gmail.com

This is an interesting group I just had an impedance issue i got help with on a project that I am working on, in summary I used CO sensors in a parking garage the rating on the comunication bus is 2000ft, When I designed the project during estimation I took a risk to strech to 3000 based on the probability that the voltage drop would not migatate me. Anyhow to make a very long story short, it turned out between my low volatge sub and my inherient nature for taking small calculated risks, the com was 3500 ft, I tried to figure out the best end of the line terminator , going back to the impedance matching topic that sparked my interest, after calling some experts, I got the matched impedance, but still need to and another 50VA transformer.... lesson learned on my part

Thanks for sharing Allan J Federman snipped-for-privacy@gmail.com

Mr. Federman, your writing verges on the incomprehensible. I have little idea what you're talking about or trying to say.

I hope communications with your customers aren't so opaque.

I think he'd be talking DC signals from the CO sensors, not impedances? But no expertise here concerning remote indicating sensors.

a e

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I don't feel so badly now, as I couldn't really figure out what he was talking about either. However it did sound interesting so if the OP could please rephrase it a little better we all might be able to participate. I always proof read my work.Lenny.