Designing a Clock (Circuits)

[EmperorIQ]

Hi,

Does anyone know how to actually implement a clock in a circuit? I've taken some circuit design classes but they've never told me how to implement a clock physicall, i've always drawn the typical
|```|___|```|___ etc, but how do i actually implement one physically on a board?

Thanks!

 

[ribbon13]

http://www.rentron.com/clock-sch.htm

 

[EmperorIQ]

No, i don't mean an actual clock, but something that triggers the clock cycles, so my D-flip-flops will work. Thanks though ribbon.

 

[JimPhelpsMI]

Hi, Pick up a LM555 timer chip and do some research on it. Most any Letters plus 555 will be the same. It fits an 8 pin standard socket. It will run from 3v to about 15v and can be used for many timer circuits. You probably only need it in a oscillator circuit. Only takes the chip, two resistors and 2 capacitors. Jim

 

[Navid]

Originally posted by: EmperorIQ
No, i don't mean an actual clock, but something that triggers the clock cycles, so my D-flip-flops will work. Thanks though ribbon.

Do you want to have a push-button switch that you press to generate a clock pulse every time?

If that's what you want, you need to debounce the switch. A switch generates many pulses because it is not an ideal switch. So, if you just use the switch to apply the power supply voltage to your flops, every time you press it, you practically generate several clocks and your circuit will behave differently than you would expect.

You can fix this so that every time you press the button, it only generates one pulse. That is called debouncing.
http://www.rentron.com/Myke6.htm

There are different ways for debouncing. I am not sure if this is what you want (and why)!

Edit:
There are hardware and software ways to debounce.

 

[harrkev]

You could also buy a commercial crystal oscillator chip. Give it power and ground, and it will give you a clock in your choice of frequencies. Check your favorite discount electronics store.

Some places to try:
Digi-Key (expensive, but they sell EVERYTHING).
Jameco (also expensive)
Electronics Goldmine
MPJA
BG Micro
All Electronics

***EDIT***
If you just need something quick-n-dirty, you can also use an inverter as a clock. Wire up three inverters in a ring. Inverter A feeds inverter B, which feeds inverter C, which feeds inverter A. This will make a VERY FAST oscillator. Slow things down by putting in an RC circuit in one of the connections. Multiply R (in ohms) by C (in farads) to get the approximate 1/2 cycle time (in seconds).