I've had this old HP 202A Low Frequency Function Generator for a number of years and thought it was about time to replace the gummy-sticky rubber power cord and see if was still operational.
I downloaded the manual http://hparchive.com/Manuals/HP-202A-Manual-SNprefix-037.pdf and got interested in its balanced output stage. I thought it might be of interest here as a possible transformerless output stage for other projects.
Here's the output stage theory of operation along with block diagram; schematic follows...
And schematic:
I think waveform inputs to the stage are unbalanced, but can't be sure.
After bringing it up slowly on a Variac and letting it cook for awhile it seems to be working pretty well and so beautifully made!
But with a top-end of 1200 Hz, I don't think there's much I'm going to use it for.
TIA!
I downloaded the manual http://hparchive.com/Manuals/HP-202A-Manual-SNprefix-037.pdf and got interested in its balanced output stage. I thought it might be of interest here as a possible transformerless output stage for other projects.
Here's the output stage theory of operation along with block diagram; schematic follows...
And schematic:
I think waveform inputs to the stage are unbalanced, but can't be sure.
After bringing it up slowly on a Variac and letting it cook for awhile it seems to be working pretty well and so beautifully made!
But with a top-end of 1200 Hz, I don't think there's much I'm going to use it for.
TIA!
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