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Old 22nd Aug 2022, 6:52 pm   #3
FRANK.C
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Join Date: Feb 2006
Location: Roscommon, Ireland
Posts: 732
Default Re: Using Hedghog Mk1 as a modulator

Hi Nick
The Hedghog II can be used as a modulator only. The original Hedghog had not this feature.
However what you were asking could be done.

I would suggest injecting the video signal at the junction of C37 and R21. A normal 1Vpp video signal can be injected at this point without any level control.
But! if doing this the signal coming from IC2 must be isolated. Probably the easiest way to do this would be to lift R66.

If you wanted to do this and have it a permanent switchable feature.
You could mount somewhere convenient a SPDT toggle switch and a phono socket for the modulator only video.
Wire the common of the switch to the junction of C37 and R21.
One side of the toggle switch going to the new phono socket.
R66 could be changed to a through hole component and mounted between IC2 pin 7 and the other end of the toggle switch.
The switch would switch between the converter output and the new phono socket.

Frank
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