Sawtooth Generator plus LED Pulser

The included switch is only needed for the sim and is required to get the osc going when the sawtooth gen won't begin after starting the transient analysis (activate the switch momentarily and the osc will start). The prototupe hardware always started and the switch was never required. The diode in parallel with the cap is optional for the sim and is used to keep negative noise spikes to within one diode drop of ground. The spikes sometimes occur during the fast capacitor discharge portion of the sawtooth cycle. On the prototype hardware, small noise spikes did exist, but there was no noticable affect on ramp slope or osc frequrncy and the diode was deemed not neccesary and therefore, not included. Apoarently, the noise spikes have a much larger affect on the EveryCircuit simulation results. I added the comparator with hysteresis and the led because the workspace was large enough and I like flashing leds. Although both the EC sim and actual prototype hardware function correctly without a res between the base and ground of the last npn xstr, it would't hurt to put one there to ensure pull down when the pnp xstr is off. Use a 20k for the EC sim and maybe a 10k or 20k for the hardware. I have added it into the schematic after the the inital release to the Community.

published 8 years ago