Amp for signal generator

[asimpson]

I wish to amplify sine wave from a signal generator 10Vpp 50 ohm load, 0.2 amp pp up to 1 amp pp for a test.
Running 0-10kHz.

Just like to build a simple circuit rather than buy expensive instrument. Might learn something.


thanks in advance

 

[VEBill]

An audio amplifier? That's only 10 watt class. 0 Hz might be tricky, but 20 Hz to 10 kHz is easy. Calibration can be with an external oscilloscope.

Or, if you choose to build, use one of those hybrid power opamps.

 

[VEBill]

Oops, I missed the 50 ohms load. That makes it just a bit more difficult.

 

[VEBill]

An off-the-shelf audio amplifier intended for 8-ohm loads would have to be 'moderately-large' (~200 watts class?) capacity to source 1.0 amp into a 50 ohm load. But there are PA amplifiers with "70 volt" outputs that might be closer match to drive a 50-ohm load.

But you still have the 0 - 20 Hz gap.

 

[asimpson]

Thanks. I'll give that a go.

 

[Skogsgurra]

One question. When you say 10 V into 50 ohm, 0.2 A. Is that the spec for your signal generator? That is how most generators are specified. Do you actually need to drive 2 A into 50 ohm? Or is all you need 2 A at the same voltage as before?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[asimpson]

Those are spec. of signal generator.

I need to drive 1 amp total peak to peak. About 20 ohm.

thanks

 

[Skogsgurra]

Is the load purely resistive? In that case, you don't need more than 10 V (if you by 1 A peak to peak mean just that) and all you need is a couple of properly biased complementary power transistors working as emitter followers. Shall try and google something for you.


Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Skogsgurra]

Check these

http://waltjung.org/PDFs/WTnT_Op_Amp_Audio_2.pdf

http://forum.allaboutcircuits.com/showthread.php?t=18042

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[VEBill]

The Walt Jung circuit is limited to about 240 mA peak output current according to the description. And with 5+10 ohms in series with the 15 volt PS, it'll never reach one amp output as drawn.

The Bill Marsden circuit with 2N2222 and 2N2907 might be hard pressed to deliver the necessary power output.

 

[Skogsgurra]

I expected the OP to do some research of his own. Just giving him directions.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[VEBill]

Point taken.

 

[Skogsgurra]

As usual, the OP needs to contact an EE. I am not so sure that the specs given correspond to actual needs. We still do not know if the load is resistive or not. If inductive and there's a need to push amps through the load at 10 kHz, a lot more voltage is needed.

The numbers we have seen so far indicate that the OP is a mechanical guy - which his handle also says.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[VEBill]

Very good points. Such current driving projects often involve loads that are eventually revealed as large coils. I'll bet you a virtual beer that you are correct in your suspicion.

Off-the-shelf audio amplifiers might be ideal in such cases. They're typically designed with good current driving capacity to keep the woofer cone under control.

 

[benta]

A look at the National "Overture" power amplifiers might be a idea:

http://www.national.com/cat/index.cgi?i=i//277

Benta.

 

[Skogsgurra]

I use the KEPCO BOPs for such experiments. They have a little problem following all the way to 10 kHz, but are OK at 5 kHz. My unit is an old one BOP 72-6 with +/-72 V and 6 A output. Use it for servo coils and such things.

Can probably be found on eBay for an easy price.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[sreid]

How about something like a Cirrus [Apex} PA07.

http://www.cirrus.com/en/products/pa07.html