# [SOLVED]Single supply triangular wave generator

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#### electronicnoob

##### Junior Member level 1
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!

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#### d123

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.

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##### Super Moderator
Staff member
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.

#### FvM

##### Super Moderator
Staff member
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.
--- Updated ---

Resistor values for ideal rail-to-rail OP

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