Measure capacitance the old-school way
Capaci-meter uses two classic decade-counters, 555 timers, and LEDs to measure and display capacitance.
We were fortunate to collaborate with Jez Siddons on this project. Jez designed this nearly-exact circuit in 1984 as a high-school project! It is still elegant and impressive as it was back then, we think. Later, he founded PEAK where he continues to designs and manufacture professional electronic component measuring equipment.
Capaci-meter was project #31 of the Boldport Club.
x2 Decade counter IC, TI CD4017BE
x1 556 timer IC, TI NE556NG4
x1 5V linear regulator, ON Semi MC78L05ABPX
x1 N-channel MOSFET transistor, Fairchild 2N7000_D26Z
x18 Red LEDs, Multicomp MCL053SRD
x2 Green LEDs, Multicomp MCL053GD
x1 9V battery clip, Keystone 84-4
x1 10-pin header, Multicomp MC34739
x4 1N4148 diode, Taiwan Semi 1N4148
x2 10µF electrolytic capacitor, Multicomp MCUMR16V106M4X5
x3 0.1µF ceramic capacitor, Vishay K104K15X7RF53L2
x1 0.01µF ceramic capacitor, Vishay K103K10X7RF53H5
x1 4700pF ceramic capacitor, Multicomp MC1206N472J500A2.54MM
x1 47pF, Suntan TS170R2A470JSBNA0R
x3 13KΩ resistors, Multicomp MF25 13K
x1 130KΩ resistor, Multicomp MF25 130K
x6 1KΩ resistors, Multicomp MF25 1K
x1 560Ω resistor, Multicomp MF25 560R
x1 150KΩ resistor, Multicomp MF25 150K
x1 1.5MΩ resistor, Multicomp MRS25000C1504FCT00
x2 16-pin IC socket, TruConnect 22-0109
x1 14-pin IC socket, TruConnect 22-0108
x1 Jumper link, Multicomp SPC20479
x1 Lovely PCB
You’ll need to supply the battery and test wires.
Assembly and usage
Pay special attention to R1-R4 and R1'-R4' so that they are fitted correctly.