Counter Circuits
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The oscillator provides a 1MHz and a 1khz clock. The 1MHz clock is used as the clock for the microcontroller and as timebase for millisecond measurement. I use a 2MHz and divide it by 2 in order to guarantee a 50% duty cycle. Then three halve HC390 are used....
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After getting some Micro Scalextric for Christmas and shortly after acquiring a vast mount of second-hand track from eBay I decided I needed a lap counter so I could race against the clock with opponents. I didn`t just want to see who could do 10 laps first....
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This is a successor of the PIC16C71 4-digit LED f-counter & V-meter. Some hard to find parts used in the previous version, which are out of production for some time, has been omitted. A rather early PIC16C71 has also been replaced by 28-pin device PIC16F876.....
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This circuit uses a synthesized sound chip from Holtek, the HT-2811. This reproduces the sound of a "ding-dong" chiming doorbell. Additionally, the circuit includes a CMOS 4026 counter display driver IC to count your visitors. The Holtek HT-2811 is available....
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As equipment becomes increasingly more compact, designers are often obliged to follow suit by reducing the size of displays. At some point, the usefulness of the display can become compromised. I, for one, dislike having to peer intently at tiny displays in....
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I needed an excuse to use the soldering iron so I figured that I might as well as make a frequency counter which is something that I`ve always wanted, but lacked in my lab. Here`s the schematic. I drew it up in OrCAD PSpice a while back. Since then, I have....
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Measuring the radiation can be made not only with expensive factory-made instrument. The simplest device (see Figure 1), can be build if you have a counter (radiation detector) type SBM-20 or similar. The circuit is powered by a 220 volts AC 50/60Hz. The....