| Electronics > Projects, Designs, and Technical Stuff |
| Clamping DC Biased Composite Video Signal Back to ground |
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| syntax333:
Hi, as the title suggests I want to clamp the DC Biased Composite Video Signal back to its original position. I have tried to clamp the signal by extracting sync information and drive a switch which connected to ground according to sync info. The DC bias which I added is approximately 5V. After trying clamp the signal back to ground DC bias drops to 2V. I want the signal at its original position which is 0V. Are there any suggestions? Thank you. |
| xavier60:
I have a circuit that will clamp the sync tip to 1V, you want to clamp to 0V? Can you show us your circuitry? |
| syntax333:
The circuit I used is shown below. I want to clamp to 0V. |
| xavier60:
The CSOUT pulses are positive going. They should not be inverted to drive the 4066. DC restored video signal doesn't tolerate much loading. EDIT: I was wrong about the CSOUT polarity. |
| dzseki:
You can use a DC coupled opamp (Au=1 or 2 depending on what output termination you want ), but with DC bias applied to the inverting pin, therefore subtracting that bias from the input signal. |
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