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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When the hours counter is reset, so is the flip-flop, making its Q output high. However that would require one extra chip for just one gate, whereas I had a spare flip-flop available which could be ab used for the same job.

TP1 is a test point at hef datasheet you hef datasheet measure the buffered hef datasheet While the clock is in run mode SET is high, opening the gate for the carry pulse.

The other sheet covers the display circuit and the power supply.


Otherwise the roll over of the minutes counter would advance the hours counter too. That means a huge parasitic series inductance for 16MHz.

In SET mode the SET signal is high, and the seconds darasheet minutes carry can dtaasheet occur because the seconds counter is held in reset.

You can download the circuit diagram here. As such, your effective dztasheet loading capacitance may be ratasheet exceeding the point where the circuit will successfully begin or sustain oscillation. This signal is fed to the seconds counter, as described below. This allows hef datasheet to advance the hours counter. The 14 stage counter is receiving a signal from the oscillator stage as I can see it on the pin 9 but doesn’t count.


This helps to tune the frequency of the time base to the correct value.

It’s output Q0 of the first decade counter IC4A. What is IC3B doing there? Navigation How to navigate Sponsors Please consider clicking on the Support Me button to show your appreciation. Note from the datasheet that the lower end of the maximum frequency at 12V is about 12 MHz the typical value is much higher, but you can’t really count on it because it is not guaranteedbut this was probably rated with device properly bypassed on a pcb.

We are only interested in two others, the Hz and the 64Hz outputs, which are used in the display jef4060 of the clock. I suggest fitting a 10nF to nF ceramic capacitor next to the hole of pin 16 and pin 8 respectively.

My way of keeping this site alive. Therefore IC9C will inversely follow the low going carry signal from the minutes counter.

But this time the maximum count value is limited to I’ve added it again. And now the hours counter.

From then on the flip-flop remains in that state, until the hours counter is reset to 0 again. IC4A divides the 1Hz pulse by This removes the breadboard from the connection entirely, and will likely be far more reliable. Home Questions Tags Users Unanswered. The Minutes Counter Next stop, the minutes counter. The Q gef4060 will be used by the display part of the circuit to suppress the leading 0 of the hours counter.

The length of supply lines is almost always more than two inches from the power supply to the breadboard. Solderless breadboards are further limited by their voltage and current ratings. 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 hhef4060, usually less than 10 MHz, depending on the nature of the circuit.


BrianCarlton Sorry, I already added the link to the datasheet in the first post, but it got lost somewhere. This not only prevents the clock hdf advancing every minute during SET mode, it also starts counting a whole new minute once the hef datasheet is set to RUN mode again.

SB-Projects – Projects – CMOS Clock – Hardware

Another link from an Illinois ECE college course states: As usual, with such a one of project, I didn’t bother to create a PCB for the project. If you can, I would strongly suggest lifting the two crystal pins bend the leads on the DIP package up, so they poke out of the device horizontallyand soldering the crystal and caps directly to them. This pulse is used to flash the colon between the hour digits and the minute digits on the display. Basically, the intrinsic capacitance of the breadboard may already be equivalent to the needed crystal load caps.

Breadboards add inductance to all the pins and force large loops in your wiring. I’ve rebuilt the circuit with a different layout on a different breadboard, and now it works with 4MHz, 11MHz and