Data sheet acquired from Harris Semiconductor. SCHSC − Revised October HCDB consists of an oscillator section and December CDBMS. CMOS 14 Stage Ripple-Carry Binary Counter/ Divider and Oscillator. DATASHEET. Pinout. Functional Diagram. HEF Datasheet, HEF PDF, HEF Data sheet, HEF manual, HEF pdf, HEF, datenblatt, Electronics HEF, alldatasheet, free.

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And now the hours counter. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. Due to large stray capacitance from pF per contact pointhigh inductance of some connections and a relatively high and not very reproducible contact resistance, solderless breadboards are limited to operation at relatively low frequencies, usually less than 10 MHz, depending on the nature of the circuit.

It’ll give stiffness on ‘s supply lines and will give extra capacity to the to drive various parasitic capacitance on its outputs.

Like I said in a comment before, you may need to start looking for the improbable, or things that you take for granted because they usually don’t fail: Lastly, the parasitic capacitance that the breadboard adds will affect the oscillator circuit, so you may have to adjust for this. I tried with some random values, from 1 to pF, and nothing.

The Q output will be used by the display part of the circuit to suppress the leading 0 of the hours datashert. Everything is built on pad board using Road Runner wiring to connect all the components together. This is generally why high frequency devices avoid breadboards.

Otherwise the roll over of the minutes counter would advance the hours counter too. We are only interested in two others, dataaheet Hz and the 64Hz outputs, which are used in the display section of the clock. Sign up using Facebook. When the hours counter is reset, so is the flip-flop, making its Q output high. The oscillator part is built as described in the HEF data sheet.


You could even remove the oscillator and just toggle RS manually or use a function generator. Another link from an Illinois ECE college course states:. BrianCarlton Sorry, I already added the link to the datasheet in the first post, but it got lost somewhere. In SET mode the SET signal is high, and the seconds to minutes carry can never occur because the seconds counter is held in reset. IC4B tries to do the same for the 0. We need 1Hz, not 2Hz, to feed to our seconds counter. At the end it will produce an accurate frequency of 2Hz on output pin 3.

Test at lower frequencies and see what happens.

SB-Projects – Projects – CMOS Clock – Hardware

Now IC9D will inverse the pulses hef datasheet from the push button. Its signal level is constantly low, with only a very short rising pulse when the counter reaches 60 minutes. And when some pin is at 1, if I raise MR, pin goes to 0. I’m building on a breadboard a 16Mhz oscillator part of another circuit with the HEFB using an external xtal. C5 is used to set the correct frequency. PeterJ 16k 20 42 We’ll have to tell the clock what time it is when it has lost all its power anyway.

Both buttons have a debouncing capacitor in parallel to make sure that every button press results in just one pulse.

But that’s a secondary problem. This allows you to advance the hours counter. Eventually the output of IC10C goes high when a button is pressed. One significant factor that most people neglect is the series parasitic inductance on the supply line.

But I think that this could be a problem caused by the breadboard as apalopohapa said. I have covered the time base and the counters here. Post as a guest Name. The Wikipedia Page on them states pF per contact pointso you may have far too much capacitance on your crystal C5 is used to set the correct frequency.


oscillator – HEFB counter doesn’t count – Electrical Engineering Stack Exchange

When the second decade reaches 6 the output of IC10A will go low. Together with this knowledge you should be able to build the clock yourself too. When the carry pulse goes high too, datasheft output dayasheet IC9B goes low briefly. Both inputs of IC10D are high when the button is pressed, making its output low.

You can download the circuit diagram here. The relative high contact resistance can already be a problem for DC and very low frequency circuits. Therefore IC3A is used to divide the frequency down to 1Hz.

This reset pulse is also used as carry to the hours counter. Solderless breadboards are further limited by their voltage and current ratings. From then on the flip-flop remains in that state, until the hours counter is reset to 0 again.

The other sheet covers the display circuit and the power supply. The problem could datashset related to testing at near the device’s maximum frequency on a breadboard. They also make proper power bypassing difficult because you have to use caps with long leads.


Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of datawheet website is subject to these policies. This allows hef datasheet to advance the hours counter.

This removes the breadboard from the connection entirely, and will likely be far more reliable. Both inputs of IC10D are high when hef datasheet button is pressed, making its output hhef4060.

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