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Uses 3161, CA3162 ICs

Even if the digital multimeters have dominated in a lot of applications, in the measurement, exist the need for existence of instruments of clue in various appliances, voltage and current, as in power supply or elsewhere. The circuits that give make this precisely the work, measure the voltage in terminal a circuit and the current that passes in his. The circuit does not present particular difficulties for somebody that has a small experience. The two circuits are the himself, with a small difference only in their input, when they have they measure voltage or current and in connection that concern decimal point.

This is a simple 30V volt meter using PIC16F676 micro controller with 10-bit ADC (analog to digital converter) and three 7 segment LED displays. You can use this circuit to measure up to 30V DC. The possible applications are on bench power supply or as a digital panel meter in various systems. PIC16F676 is the heart and brain of this circuit. The internal adc of the mcu with a resistor network voltage divider is used to measure the input voltage. Then 3 digits of comm anode 7 segment display is used to display final converted voltage. As you can see in the schematic the displays are multiplexed with each other. It means we switch on one display and put the corresponding digit on this while other two displays are off this cycle goes for each of the displays.

Frequency counter is a very important test instrument for Radio Amateurs, especially those who wish to develop or test circuits. There are lots of frequency counters in the market but building one was never so easy & exciting with Microprocessors doing lots of work for us.

This project was published in Electronics Australia in Oct/Nov 96. It is a 32 Channel, 40Mhz, fully PC controlled TTL/CMOS logic analyzer with internal/external triggering and trigger delay. Internal triggering is fully maskable (High/Low/Don't Care) on all 32 channels. The whole things fits on one single sided PCB with virtually no wiring!

This circuit is ideal for adding a low cost frequency display to a function generator or other design. I doubt if it is possible to get a cheaper design using off the shelf components!. In fact, I challenge anyone to make a cheaper design using garden variety components!. The upper frequency limit is dependent upon the upper limit of the 74HC390 chips which is roughly 40MHz.

This project is nice and small frequency counter that reads frequency from 1 Hz to 50 MHz that I have modified from original designed by Weeder Technologies . I have designed new PCB to fit with 16X1 LCD and change source code for compatible with new small PCB Specifications - Auto-ranging with floating decimal point. - Up to 7 digits displayed on 1X16 LCD. - Auto-adjusting gate speed (0.1 sec to 1 sec). - Microcontroller-based circuitry provides for simplicity, ease of assembly, and highly stable readout. - Sensitivity approximately 100 mV RMS (100 Hz to 2 MHz), 800 mV RMS @ 50 MHz. - Input overload protected.

The prescaler kit is a simple divide by 10 ECL circuit which can be used to extend the range of most PIC based frequency counters from 50 MHz up to 500 MHz. The kit uses surface mount components except for the 78L05 regulator.

This new 50MHz Frequency Meter is autoranging and displays the frequency in either Hz, kHz or MHz. This makes the unit easy to read, as it automatically selects the correct range for any frequency between 0.1Hz and 50MHz and inserts the decimal point in the correct place for each reading. Note that although we have specified this Frequency Meter at 50MHz maximum, most units will be capable of measuring frequencies somewhat higher than this. In fact, our proto-type meter was capable of making frequency measurements to above 64MHz.

Built around a single 8038 waveform generator IC, this circuit produces sine, square or triangle waves from 20Hz to 200kHz in four switched ranges. There are both high and low level outputs which may be adjusted with the level control. This project makes a useful addition to any hobbyists workbench as well.