[SOLVED] Single supply triangular wave generator

Hi guys, I am having a little problem designing a triangular wave generator with a single supply. I intend to use a Schmitt Trigger Comparator circuit and an inverting integrator to design the circuit.

• Duty cycle = 0.5
• Frequency = 8.5kHz
• Supply voltage = 12 V (single supply operation)
• Vmax = 7.3V
• Vmin = 3.1V

All I know for now is the UTP = 7.3V and LTP = 3.1V.
I think I need an negative input for the inverting integrator for it to have a positive gradient part of my triangular wave. Is there any other way to do it?

Any help is appreciated. Thanks!

Hi,

Can you bias it at an appropriate level for the output signal to stay above ground, the same as a single-supply inverting amplifier, or the below schematic? The maths might be 'lots' of fun to trawl through... I found it hard enough figuring out how to do the formula for a single-supply inverting amplifier that only had to go from +1Vin = 0Vout, 0Vin = +1Vout - I still haven't figured out how to work out +1.5Vin = 0Vout, +0.2Vin = +1Vout... This is from 'Op Amps for Everyone', might be of help to think it through, maybe not.



Maybe 'Single-supply Op Amp Design Techniques' (sloa030a.pdf) might help somehow, but it has no integrator in it, unfortunately. I have to confess that I found the maths approach off-putting, hopefully it'll be more your cup of tea.

This triangle wave generator is from the Circuits menu of Falstad's simulator. Raise the waveform into the positive region by applying a positive voltage instead of ground connection at the inputs.

Yes, the ground connected OP inputs can be connected with a voltage divider to Vcc/2. The schmitt trigger resistor ratio must be adjusted for the intended output voltage range and RC time constant for the frequency. An additional resistor from ST non-inverting input to ground should be added to accountt for the requested asymmetry.


Resistor values for ideal rail-to-rail OP