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3 votes
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Prolific PL2303 knock-off USB-TTL adapter without timing crystal

There are a number of USB-TTL serial converters which do not require a crystal. For example this lineup from Prolific in Taiwan, with about 9 different part numbers. Here is a datasheet of one that ...
Spehro Pefhany's user avatar
2 votes

What is this chip enable circuit doing? (old TTL, with diode, with pull-up?)

Your are correct, it is a wire-AND. The classic circuit of this type would be two diodes (one for each input, logic and A) and one pull-up resistor. Both diodes have to be high for the result to be ...
AnalogKid's user avatar
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5 votes
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What is this chip enable circuit doing? (old TTL, with diode, with pull-up?)

It's a wire-or circuit, where the gate can drive a dominant '0' in place of the signal in 'A'. So you get: ...
hacktastical's user avatar
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0 votes
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recognising patterns in TTL logic analog circuit

It seems to be a simple inverter. Assuming no other connections, resistors and supply as shown, we can simplify the circuit as so: simulate this circuit – Schematic created using CircuitLab ...
Tim Williams's user avatar
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