I wish to invert a video signal, keeping the signal positive.
Initially I believed the analogue signal would be 0v->5v, so I used the inverting input on an op-amp, and biased the non-inverting input to be approximately 2.5v. This worked well, but then I discovered that depending on the analogue source, the voltage range can be 0v->2v or 0v->3v.
This means that biasing the non-inverting input to a single voltage doesn't work. Can anyone think of a way to use an op-amp so that the signal can be inverted (180o phase, keeping it positive though), whilst retaining 0v base?
I have searched for similar questions, but they all seem to be based on people that have a fixed source signal range.
I'm attempting to convert old CGA arcade Nintendo RGB signals that use untraditional inverted colours. Each one of these colours is created from multiple TTL outputs (with different resistors), and through a transistor. Arcade monitors accept 1-5v p-p signals, but after measuring multiple sources they tend to be 0v to 2 or 3v max.
This means that on a standard monitor, black is displays as white and vice versa. Therefore, if we imagine that the signal goes from 0v to 2v, I need to invert that so that is goes from 2v to 0v to invert the colour.
The composite sync signal is negative (standard), and so doesn't need to be altered, and the sync signal is 15.75khz, so we're not talking about large bandwidths.