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 »
This is a low frequency amplifier with an adjustable transimpedance that is intended to be used to take relative measurements of a wide range of photo currents. Not having many parts, this amplifier can be put together in a short amount of time. Find updates at www.projects.cappels.org Introduction I needed to make some relative optical
Photocell Amplifier using microcontroller Read More »
Measure current vs voltage or voltage vs current over limited range with good accuracy. This was built on a phenolic board which was mounted on a plastic box. The box serves two purposes: It holds the circuit off the workbench, and it makes a nice, stable mount for the potentiometer. Find updates at www.projects.cappels.org I
A SIMPLE MANUAL CURVE TRACER using microcontroller Read More »
