This voltage to frequency converter is designed to be connected to a frequency counter to display the voltage value being measured.
This converter-counter combination produces a cheap but functionally complete digital voltmeter. The circuit delivers TTL compatible pulses which are 5 ÁS wide.
The pulse frequency is proportional to the DC voltage being measured. The conversion factor is 10 kHz per volt. When the input level is 0 V the frequency output is 0 Hz.
The resistor R2 (together with C1) determines the conversion factor and has the value of around 90 K. To achieve best results use a metal film resistor for R2 in series with a multiturn
trimmer resistor. This multiturn resistor will enable you to set the correct resistance value. Resistors R9 and R14 must be metal film types.
- Connect the output terminals to the digital frequency counter.
- Set the frequency counter to the appropriate range (ex. 100 Hz).
- Short the input terminals of the converter module together.
- Adjust P1 so that the output frequency is 0 Hz as displayed by the frequency counter (maximum allowable is 2 Hz).
External Wiring Layout
A typical combination to build a functional digital voltmeter using a digital frequency counter as the display module.
Electronic Circuits volume 1.0 - Circuit Nr. 99
The complete data of the electronic circuit described above can be found in the following book and is available from Amazon.com.
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