Styx said:
We need some more infomation!.
What do you want this "noise" for. 23V is quite high a voltage (for a signal) - what is it feeding? why do you need a noisy signal for?
Eventually he's supplied a little more information (in a PM, but I thought I'd post a reply here).
He's wanting to build a cellphone 'jammer', and wants a varying voltage (either random or sawtooth) from 0-23V - presumably for tuning on a varicap diode in an oscillator circuit?. It's also for the course he's on, so doing his work for him seems rather like cheating?, but a few suitable hints should set him on the way.
This bears no resemblance at all to any of his previous questions, which is why we weren't getting any where!.
Anyway, here's one simple solution to the problem:
Use a constant current source from a 24V (or so) power supply to charge a capacitor, the top end of the capacitor is the tuning voltage for the varicap.
Place an NPN transistor across the capacitor, collector to the top, and emitter to ground.
Feed the base of the transistor from a squarewave oscillator, a 555 would be suitable.
When the base of the transistor goes high it turns ON, discharging the capacitor, when it goes high the transistors turns OFF - allowing the capacitor to charge in a linear, giving a nice sawtooth ramp.
The constant current, capacitor value, frequency and mark space ratio of the oscillator, will all require calculating (or finding by experiment).