[sdiy] Generating +5V gate signals from +3.3V logic

[Steve Lenham]

>> Ok, so what do you do for gate outputs then, Andre?
>
> What Tony Allgood does in some of his modules : 75 ohm resistor
> inside the feedback loop. The part I haven't figured out is how
> to generate a +5.00 V (or, if possible +5.000 V) voltage without
> using too many components. I suspect a voltage reference is
> needed plus one comparator and one op-amp per gate.

Why not just use a CMOS analogue switch to gate your chosen reference 
voltage to the output buffer opamp?

If you are using a non-inverting opamp, the input impedance can be made 
v.high, so switch on-resistance is not an issue and cheap 405x/74HC405x 
devices can be used.

You get three or four switches in a single package plus, if you choose 
HCT parts they will accept Tom's 3.3V logic without further translation.

Cheers,

Steve L.