Summary A three-digit initial state, determined by three 4-position dual inline (DIL) switches, is set by pressing Switch 1 (SW1). Pressing Switch 2 (SW2) starts a count down to zero. When zero is reached, the light emitting diode (LED) lights up. The progress of the count is shown by a three-digit seven-segment liquid crystal display (LCD). This improves […]
POR
Summary The initial state of an SR (set-reset) latch is, in principle, indeterminate. The circuit is a SR (set-reset) latch with a power-on reset (POR), so that the initial state after power-on is determined. Circuit Schematic Transistor T3 is off while capacitor C1 charges through resistor R5. Consequently, the voltage at the collector of T1_L […]
Countdown Mk 1
Summary A three-digit initial state, determined by three 4-position dual inline (DIL) switches, is set by pressing Switch 1 (SW1). Pressing Switch 2 (SW2) starts a count down to zero. When zero is reached, the light emitting diode (LED) lights up. The progress of the count is shown by a three-digit seven-segment liquid crystal display (LCD). […]
Adder
Summary The circuit adds two four-bit numbers. The input is by means of a single eight-position DIP (dual in-line package) switch. The output is displayed using a five-bar LED (light-emitting diode) bar graph. Circuit The least significant digits are highest in the image. Switches 4 to 1 are one input and switches 8 to 5 are the other. […]
Tone
Summary The circuit drives a speaker to generate a tone. The frequency of the tone can be varied by adjusting a trimmer. Circuit Schematic Stripboard The stripboard size is 9 tracks of 25 holes.
Clock
Summary The circuit switches between lighting one of two light emitting diodes (LED). The frequency of the switching can be varied by adjusting a trimmer. Circuit Schematic The circuit was originally intended to be powered by four AA batteries, each with a nominal voltage of 1.5 V (6 V in total). The batteries are relatively […]
SR latch
Summary The circuit is a SR (set-reset) latch. The input is by means of a two tactile switches (set and reset). The output is displayed using two LEDs (red and yellow for Q and not Q). Circuit Originally, the power connector was a two-position screw terminal (as in the images above). This was replaced with […]