Op Amp 741

[CDRIVE]

Those meters are all beautiful. Like Dave, I haven't seen one in many years but I do remember when they were common in industry. If I'm not mistaken the 400Hz meters were found in military aircraft application as they used both 28VDC and 120VAC @ 400Hz. I think the latter was (is?) used for power while the planes were on the ground and plugged into a 400Hz source.

I noticed your avatar. Are you a ferroequinologist? If so were they common in railroad applications too?

Anyway as Dave said, OpAmps aren't used as a power source. Especially at mains level voltages. Do the meters include any specs on them like input voltage, current or input resistance / impedance?

Chris

 

[CDRIVE]

Oops, I see the meters say 115 to 120V on the face. Then resistance, impedance or input current at or near the operating frequency would be useful info.

Chris

 

[colum]

The 741 is just going to buffer Hertz signal from a signal generator IC and this 741 may not even be necessary.

You are correct about feeding current into meters. The last motor that I was involved with drew 700 Amps at 3 Ph and had all panel meters that were designed for such power with very heavy wiring and resistors and a circuit brkrs
The machine was a huge Synchronous motor driving a double acting single stroke compressor from the 1930s.
Thank you for your understanding of my limited Electronic knowledge...Jeff

 

[Alec_t]

Having now seen the meter pics it's clear that each responds to less than an octave frequency range. Therefore I think they could be driven with a square-wave signal, since harmonics of the fundamental frequency shouldn't affect them. As I said previously, a 100V-ish square-wave would be much simpler to generate. A 555 driving some power MOSFETS might do the job?

 

[CDRIVE]

Jeff, you seem to have an aversion to answering questions. All the photos are nice but this is going to be a long laborious thread if you don't do so.

Chris

 

[davenn]

Jeff

since you still wont answer my and other Q's, I'm going to close this thread
if you had answered Q's when asked the topic would have been probably resolved many posts ago
it's very frustrating for those trying to help you

PM me when you are finally prepared to answer all the Q's asked but not answered and I will reopen the thread