Generate Pseudorandom Voltage

[Teh0therside]

I'm looking to generate a pseurandom voltage in the range of ~0 to ~2V as cheaply as possible. I read about one option that used a resistor network with a shift register to do this but I was wondering if anyone had any simpler suggestions.

Thank you

 

[Sceadwian]

The simplest method would be to use a micro controller, then you can do the random number generator in software (very easy) and the output could be a simple 1bit DAQ (PWM and vary the duty cycle)

 

[Teh0therside]

Thank you for your suggestion. Can you think of any way to do it with discrete components and op-amps? Due to the nature of what this will be used for, microcontrollers are not really a viable option. I tried to do something using the voltage noise generated by an LED with an op-amp but it didn't work too well.

 

[Reloadron]

Using discreet components you could use a chip like the 74HC161 configured as a ramp synthesizer which when clocked would produce 16 outputs. If you fast clock and stop the output will be a random voltage between 0 and whatever you set the resistors for. It would use 8 resistors. You would randomly get one of 16 possibilities between 0 and 2 volts. I am just not sure exactly what you want? There are a number of ways to do it using discreet components without a high parts count.

Ron

 

[Teh0therside]

Sorry for being so vague. The output of the random voltage generator will drive the input of a driver IC. Depending upon where I insert the random voltage, it could be in the range of 0-100mv or preferably .6-1.1V. There isn't any timing circuitry in the device so interrupting an IC like that isn't ideal. I don't need too many discrete values for the random voltage and 16 would be more than adequate. Do you know of anywhere I could find these numerous discrete options?

Thank you.

 

[Reloadron]

The best I can suggest using discreet components would be along the lines of the attached image. V2 simulates a clock pulse. The likely ideal way would be using a uC as was suggested. Each time the chip is clocked a different voltage appears at Vout.

Ron

 

[alec_t]

You could use a counter clocked by a fast clock, plus a latch to latch the count when enabled by a slower clock asynchronous with the first. Use weighting resistors to convert the latched count to an analogue voltage.

 

[simonbramble]

Do you want a random digital output (ie only 1 and 0) or a random analogue output (ie any voltage between 0 and 2V, varying randomly)?

A Zener diode is a good random noise generator. Nothing Pseudo about it. It will be completely random. YOu can amplify that with an LM324 to get the right voltage level. Just hook a reistor between Vcc and the Zener and put Zener to ground and read off the voltage at the junction

 

[4pyros]

There isn't any timing circuitry in the device so interrupting an IC like that isn't ideal.

Are you trying to BEND somthing?

 

[Sceadwian]

Due to the nature of what this will be used for, microcontrollers are not really a viable option.

Could you explain the logic behind that? Knowing what you're trying to do is often a lot more helpful then spending hours trying to guess what it is you're trying to do.

 

[canadaelk]

What is a "pseudorandom" voltage anyway. Why not random, much easier to do. E