Re: Amps and Ohms

Yes, not too many folks know it was an audio oscillator.
audio test equipment seems strange to folks that think of
HP today. In the past I have had MANY pieces of HP
audio test gear.

Eddie

Christopher "Torroid" Ott wrote:
That would be an audio oscillator. It was the first product to come from "the garage". I've heard it was in common use well into the 60's.

I've got the schematic around here somewhere. It was really simplistic by today's standards.

Chris


"Eddie Runner" <eddie@xxxxxxxxxxxxx> wrote in message news:fRL0j.355$NY.119@xxxxxxxxxxxxxxxxxxxxxxx
Normally a bench tech would measure power with a dummy load and a volt meter. There really isnt a need for a scope, but many use it just to
watch the waveform for anything strange during testing. I dont think
I have seen a tech try to measure power on a scope itself, although
you could take the time to calibrate the screen marks to voltage but
anyone with a scope probably have a wheelbarrow load of meters and that
way easier....

BTW, a little trivia...
Since you worked for HP, can you tell me what the first thing they
build commercially? Hint, it was test gear!


Eddie

Christopher "Torroid" Ott wrote:
"Eddie Runner" <eddie@xxxxxxxxxxxxx> wrote in message news:1070j.128$4q5.22@xxxxxxxxxxxxxxxxxxxxxxx
Mariachi wrote:

the only way to prove how much power you are using is to use an
oscilloscope.
How do you do it with an oscope??
Just Curious.
Eddie
If you want to measure power, you'll need a current sense resistor (non inductive) and a two-channel digital o'scope with the ability to multiply the two channels. I seem to recall that either Tek or Fluke had a scope which was optimized for this, but that's been some time ago. Most of the PC based scopes can do this as well. Pretty straightforward from there. Set the volts/division as needed to correctly scale the CSR and hook up a signal generator to the amp.

If you have HP Vee or Labview or something similar, it would be pretty easy to setup a jig to automatically measure power for virtually any configuration of amp and speaker.

As a side note, I spent 2 years at HP working on a tool to measure the energy delivered to inkjet resistors (on the silicon printhead) which did almost the same thing as I described above, only with a bunch more detail and about $4million invested. Inkjet is big money baby!

Chris


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