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| Level shifting |
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| syntax333:
Hi, what is the best way to level shift an Composite signal which includes AC and DC signal? (Adding DC bias to CVBS signal) |
| Rerouter:
If your just adding a DC bias to it, the simplest way is a resistor divider for the DC with an AC passthrough (capacitor) For more detailed information you can look at things like TV antenna amplifiers that require a DC supply to power to mast antenna, they just use a capacitor for the signal and feed in the DC voltage through a resistance. |
| vk6zgo:
--- Quote from: syntax333 on December 23, 2018, 12:05:37 am ---Hi, what is the best way to level shift an Composite signal which includes AC and DC signal? (Adding DC bias to CVBS signal) --- End quote --- Build a keyed clamper circuit, but instead of clamping the blanking(or black level for NTSC) to zero volts, clamp it to whatever DC voltage you require. This was quite commonly done back in the day. PS:- Reading your other thread, it was suggested to clamp the sync pulse tips------- this is the alternative to clamping black level, but remember, with that method, if you are trying to restore your video signal to standard levels, you will need to clamp the sync tip to around -300 mV. |
| syntax333:
Problem is that when I use the circuits like Bias tee, they completely purifies the signal from DC. However, that is not what I want. I attached the signal that I am working with. I just want to shift the level of it. Bias tee circuit eliminates the DC components in the signal. |
| syntax333:
Thank you for your suggestion, I was trying to find easier solution but it seems I have to do it like you said. Is there any reference that I can use to build that circuit? It would be great. |
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