I came across the Super Probe two weeks ago, and just had to make one. I had a bunch of the PIC 16F870 microcontrollers left over from an earlier project, and the rest of the parts were all easily found in my parts collection.
It is a really simple circuit, with so many useful features:
- Logic Probe (L < 0.8 V, H > 3.7 V, P > 0.5us pulse)
- Logic Pulser (0.5 us pulses at 5, 50, 500, 5k Hz)
- Frequency Counter (8 digits)
- Pulse Counter (8 digits)
- Voltmeter (max 5 V, readings are a little high)
- Diode measurement (measures fwd voltage using 5V supply via 10k resistor)
- Capacitance measurement (1nF to 500uF, approx 100pF resolution)
- Inductance measurement (100uH to 999.99mH, but not very accurate)
- Signal generator (0.5 V square ware @ 500 Hz)
- NTSC video generator (white dot pattern)
- ASCII test pattern (A-Z then CR/LF at 1200, 2400, 4800, or 9600 baud)
- Midi test output (plays middle C on selected midi channel)
- R/C servo test output (approx 770 to 2300 us pulses @ ~28 Hz for servo control)
- Square wave output (1 to 9999 Hz 5V square wave)
- Pseudo random output (10 kHz PRNG)
- IR test output (38 kHz 50 % duty cycle square wave for IR receiver testing)
- PWM test output (6 kHz square wave with 3 % to 97 % adjustable duty cycle)
In addition to the PIC, you just need 4 common anode 7-seg LED displays, a 20 MHz crystal, and a few resistors, caps, etc.
I found the display to be a bit dim, but the MAN6610 7-seg displays I used were quite old and would be rated quite low in brightness. I left off the LM2931 regulator as I will just power it off 5 V, and so I actually put a PIC ICSP connector on the end of the board for re-programming, and an easy way to connect power.
We are looking to make up a PCB for this so that members can make their own. It is a bit of a pain wiring up the 7-seg LED’s (using the LTC4627 would help a lot).
- Kean