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Old 11th Sep 2019, 7:48 pm   #1
OldTechFan96
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Default Adding Sweep Out To A Hameg 203-4

I'm looking to add a sweep output to my Hameg oscilloscope so that it can be used with a wobbulator.

The max sweep output from the Hameg is 4.4V at 200ms/cm to 1.5V uv/cm. This is too little to drive the reactance valve of the wobbulator.

Chris55000 suggested a "Dual Op Amp Preamp DC Amplification Board NE5532" and a 741 op amp. This will be ordered soon.

I can feed it +12V and -12V from the scope's PSU. I'm not sure about L+R inputs and outputs. I know where the sweep signal comes from.

Has anybody done this before?
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Old 12th Sep 2019, 10:53 am   #2
mhennessy
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Default Re: Adding Sweep Out To A Hameg 203-4

The NE5532 is a dual op-amp, so a 741 won't fit that PCB.

Happily, there are plenty of dual op-amps that have the same industry-standard pinout as the NE5532, such as the MC1458 or LM358.

Needless to say, an NE5532 would be wasted here. Note that being optimised for low distortion audio, an NE5532 draws 8mA, which is quite a lot compared to an LM358 (0.6ma).

Not sure you need a dual op-amp for this application - a single ought to be fine (I'm assuming you just want to increase the amplitude of the internal sweep signal). In which case, you'd ignore one half of the dual op-amp, so take the output from whichever channel you've gone in on. Make sure the circuit is DC coupled.

Personally, I'd just use a small bit of Veroboard for this. It's only one 8 pin chip and 2 or 3 resistors and perhaps a couple of decoupling caps. Somewhere at home, I think I've got an old RS op-amp PCB that takes a single op-amp and you configure it however you like by installing the appropriate components - yours for P&P.
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Old 12th Sep 2019, 11:26 am   #3
OldTechFan96
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Default Re: Adding Sweep Out To A Hameg 203-4

I think I do have all of the bits apart from the Veroboard. I am interested in the PCB you mention.
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Old 12th Sep 2019, 1:08 pm   #4
mhennessy
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Default Re: Adding Sweep Out To A Hameg 203-4

I've found some details of the PCB: https://uk.rs-online.com/web/p/audio...dules/0434065/

There's a link to the datasheet on there. As you can see, it's just a case of fitting the passive parts you need.

If you'd like it, send me a PM with your address and I'll get it posted. It might take a few days - it depend on when my wife can get to the post office.
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