sync inverter for the QL

For some unknown reason, the Sinclair QL (and perhaps some other personal computers) provides positive, instead of the usual negative, field synchronizing pulses to the monitor. Inverting these pulses with a suitably fast NAND gate or inverter is, of course, no problem. What is a prob- lem is where to power this gate from: a special supply would be nonsense. However, in the circuit proposed here, the gate is supplied from the sync signal itself. A monitor with TTL input for the sync signal draws only a very small current at logic 1, so that the additional load presented to the input pulse by the diode and electrolytic capacitor is inconsequential. Instead of the HC-MOS gate shown, it is also possible to use a buffered 5V— OV— — 4V — ov sync inverter for the QL CMOS gate, for instance, a type HEF401113. Standard CMOS devices, such as the 4011, cause a very small delay, which in practice does not mat- ter, and certainly not with a field sync signal. Note that it is important...