#222 StairStepGenerator

Generate a stair-step waveform with analog components.

Notes

Once again I’m inspired to go and build a circuit by yet another great tutorial from w2aew.

I won’t try and repeat the circuit description here - see the video and attached notes. Suffice to say, it is quite an ingenious combination of 3 sub-systems:

• a “high” (265Hz) frequency pulse (555 timer) provides the charge to step-up the output
• the step pulse feeds an OpAmp pulse integrator/accumulator
• a low frequency pulse generator (OpAmp oscillator) provides the reset pulse that clears the accumulator and resets the 555

I’m using an LMV324 opamp, which gives decent rail-to-rail performance. It has a maximum supply specification of 6V, hence I’m running the circuit at 5V only.

Performance

This is a trace of the circuit on a breadboard (a little noisy). But it works!

In this trace:

• CH1: 555 timer signal
• CH2: reset pulse
• CH3: output

Construction

Credits and References

• #231: Circuit Fun: Stairstep generator using 555 and op amps - inspiration for this circuit
• annotated circuit - by KL0S
• LM555 Datasheet
• LMV324 Datasheet