The circuit is fairly simple and should only take you about 10 minutes to wire up. The pot at far right is not used in this circuit.

OK; what’s a "window" comparator? We’ve had a look at two variations of standard comparator circuits in the December 2000 issue and saw how they switch their outputs when the input goes above or below a reference voltage. Typically, a comparator’s output might be made to switch high when its input goes above +6V and a circuit for this is shown in Fig.1 on p75 of the December 2000 issue.

As it happens, there were two comparator-based circuits in last month’s issue. Firstly, the Li’l Pulser train controller is based on two comparators connected to generate a PWM (pulse width modulated) waveform and secondly, the Bass Blazer frequency display has a whole bunch of comparators driving LEDs in four columnar arrays. There is no reason why you could not hook up the key parts on these circuits on your Protoboard and then, if you have an oscilloscope, see if you can duplicate the example waveforms.