This is a handy companion for a digital voltmeter. Its allowed me to do a lot of things I used to use my oscilloscope for, and in addition it measures voltages to much greater precision.Using an LM324 quad op amp, this peak detector provides 2% measurement accuracy on square waves from 5 Hz to 20 […]
Precision Audio Frequency Peak Detecting Probe using microcontroller Read More »
Encased in a pencil box to keep the point-to-point wiring on the back of the board from shorting to wires and things on the workbench, the plastic case also holds the offset and gain post as well as the input connector and the switches that switch on the near-zero and near-full scale references. I wanted
HF AC Millivoltmeter Adapter using microcontroller Read More »
Specifications Input: AC, DC or AC+ DC to > 10 KHz Ranges: 200 mv, 2V, 20V, 200V, 600V full scale Accuracy: ±1%, depending on divider resistor selection Crest Factor: 1 to 3, up to 5 with degraded accuracy Input impedance: 1 Megohm shunted by 20 pf Battery drain < 300 uA Introduction The DVMs in
TRUE RMS-TO-DC Adapter For DVM using microcontroller Read More »
Briefly, • AC True Watts using two quadrant multiplier • Optimized for 120 VAC (can be changed) • 15 watt full scale (can be changed) • Uses DVM floating on AC Neutral as display • Requires moderately high level of analog circuit skill • Very inexpensive Find updates at: www.projects.cappels.org Introduction I am doing some
A Pretty Good Wattmeter For Bench Use using microcontroller Read More »
Overview After finishing Little More Serious Frequency Meter I had planned to make a suitable preamp and prescaler for it, and set about to gather ideas and parts. I was inspired by one fellow who had built the meter and the 2 line X16 character LCD display to show the output, succeeded in designing a
Its built into a plastic project box with an aluminum cover (on the bottom). The controls are as follows: Large golden knob is coarse tuning, small black knob with a blue index stripe is fine tuning, the green LED is the power on indicator, the slide switch is the on/off switch. The small black knob
HF/VHF/UHF TEST OSCILLATOR using microcontroller Read More »
I needed a way to measure hand-wound RF inductors in my second lab, and since I would only be doing this occasionally, I didn’t need anything fancy, and since once a friend finishes his AT90S1200-based design, I plan to make one myself, I figured I’d use this for less than a year, so I didn’t
RF Inductance Meter using microcontroller Read More »
The “Battery Good” checker. When the button is pressed, the green LED will glow if the battery voltage is above the preset threshold. This version has a higher parts count than the “Battery Low” version, but a bonus is that it can drive an LED to be very bright, and the luminance is independent of
Battery Checker Circuits using microcontroller Read More »
A related article on this site: True RMS-To-DC Adaptor for DVM Introduction This project came about when I needed to perform some reliability tests on some headphones according to IEC 268-7. The test requires operating the headphones at their rated input power for a number of hours using clipped pink noise, and muting the noise
A Noise Generator per IEC 268-1, IEC 268-5, and IEC 268-7 Read More »
This is a means of testing AC mains operated circuits at variable AC voltages, and it also provides isolation to allow safe measurements of that circuit. A fused isolation transformer and a variable auto transformer connected together in a grounded, fire safe box. What more could you ask? Find updates at www.projects.cappels.org Introduction
An Isolated Adjustable Auto transformer using microcontroller Read More »
