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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Please consider clicking on the Support Me button to show your appreciation. It must be a problem so silly that’s too evident for me to see!!

OK, that’s enough for this one page. Post as a guest Name. IC2 forms hef datasheet time base oscillator and first pre-scaler stage.

It doesn’t really matter whether we use a rising or falling edge here because this carry pulse is very short.

IC4B tries to do the same for the 0. Sign up or log in Sign up using Google. This makes the output of IC10C constant low, except during the carry pulse. Another link from an Illinois ECE college course states:. This allows you to advance the hours counter. They also make proper power bypassing difficult because you have to use caps with long leads. This pulse is very short because its cause is removed by the reset almost instantly.

The Wikipedia Page on them states pF dahasheet contact pointso you may have far too much capacitance on your crystal.: As such, your effective crystal loading capacitance may be far exceeding the point where the circuit will successfully begin or sustain oscillation.


I would make sure the capactor values C6 and C7 are within the range reccomended in the crystal data sheet.

This signal is fed to the seconds counter, as described below. In SET mode the SET signal is high, and the seconds darasheet minutes carry can never occur because the seconds counter is held in reset.

IC4A divides the 1Hz pulse by I don’t need the output of the seconds counter itself, because I do not have a seconds display. I’m building on a breadboard a 16Mhz oscillator part of another circuit with the HEFB using an external xtal. You could even remove the oscillator and just toggle RS manually or use a function generator.

The Time Base IC2 forms the time base oscillator and first pre-scaler stage. And now the hours counter. Together with this knowledge you should be able to build the clock yourself too.

PeterJ 16k 20 42 This is a nice 0. Now IC9D will inverse the pulses coming from the push button. Next stop, the minutes counter. What is IC3B doing there? The Wikipedia Page on them states pF per contact pointso you may have far too much capacitance on your crystal You can download the circuit diagram here.

We need 1Hz, not 2Hz, to feed to our seconds counter. While the clock is in SET mode there won’t come any carry pulses from the minutes counter and that signal is constantly high. That means a huge parasitic series inductance for 16MHz. The Hours Counter And now the hours counter.


This will increase the stability of your clock. Its signal level is constantly low, with only a very short rising pulse when the counter reaches 60 minutes. It’s a bed side table clock, I don’t need it to datazheet up the entire room at night, you know. Email Required, but never shown.


HEF Datasheet, PDF – Alldatasheet

Axeman I’m happy you got it working! This reset pulse is very short, because once it is high, the counters are reset and the reset pulse is gone again. This is generally why high frequency devices avoid breadboards.

Therefore IC9C will inversely follow the low going carry signal from the minutes counter. It is very important to use 0 tempco capacitor for C4. TP1 is a test point at which you can measure the buffered One significant factor that most people neglect is the series parasitic inductance on the supply line. This page will describe sheet one in detail, while the next page will adtasheet sheet number two.

Everything is built on pad board using Road Runner wiring to connect all the components together. Home Questions Tags Users Unanswered. BrianCarlton Sorry, I already added the link to the datasheet in the first post, but it got lost somewhere.

C5 is used to set the correct frequency. The clock can be in one of two different modes, in Run mode or in Set mode.