hitwaterfish

Hi all:

i want to build a pulse generator using NE564, and the frequency of the pulse is from about 500KHz to 10MHz, could you tell how to use the NE564 as a pulse generator?

Thanks

ericgibbs

hi,

Download the datasheet from www.datasheetarchive.com

Example of freq multiplier.

Eric

EDIT: datasheet attachment, Page 9

hitwaterfish

Eric,

thanks very much!
but i couldn't find the datasheet i want, can you help me?

Hero999

He's attached the datasheet.

Anyway don't be lazy, Google knows.
http://www.google.com/search?client=...utf-8&oe=utf-8

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hitwaterfish

Eric,Hero999,

Thanks very much. I am now dealing with the circuit but the output frequency do not change when I change the input frequency. And the output frequency is about 10MHz. (When I change the value of Co, the output frequency will change.) How can I change the output freq with changing input signal.

I used the circuit of Figure 12 in the datasheet(NE564).


waterfish

Roff

What did you use for the frequency divider?

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Ron

hitwaterfish

For test, I just connected pin 9 to pin 3 directly. So N=1, the output frequency would be equal to input frequency. But even I removed the input signal, there was also output signal as I mentioned before.

ericgibbs

hi,

Insert a divider ic as shown on fig12. The Vco= f = N [divider] * fT[ the osc input freq]

If you use say, use parallel load dividers, you can set the N value being loaded into the divider using bit switches or bin/bcd switches.

A HEF4059B programmable divide by N counter would be a suitable ic for a final product.

[you could use a simple divider to experiment]

Eric

hitwaterfish

Hi Eric,

I used a 74HC4060 as the divider, but the problem was not solved. I found that the output frequency only changed when I changed the value of Co.

waterfish

ericgibbs

hi,
Im puzzled why the cct in Fig12 is not operating in way its described.

As I havn't got a NE564 on the shelf I cannot duplicate your setup.

Looking on the web, google, there are lots of application notes on the NE564.

These may suggest a cure.

I'll keep looking, will come back if any succes.

Eric

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Roff

The output is TTL compatible. It is not 74HC compatible. You need to use a 74HCT frequency divider.
This part is a phase locked loop (PLL). If you don't have experience with PLLs, I'm not surprised that you are having difficulty. You are probably better off leaving out the frequency divider to start with. As the divider ratio N goes up, the loop gain goes down, and lock is more difficult to obtain. I'm not sure how high N can be and still have the part lock.
Do you know that, if you set the VCO free-running frequency to F, and the divider ratio to N, that the input frequency must be F/N? What are you using as a signal source? And why do you want to use a PLL to generate your pulses?

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Ron

ericgibbs

hi Ron,

Have you had the opportunity to look at the HEF4059B as a suitable divider for the NE564..

I have used the HEF4046 in the past for PLL work, never played with NE564 device.

Eric

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

Roff

Eric, I have to confess I have never used the NE564, but I used to do a lot of PLL design, and I know that PLLs are finicky, especially when the feedback divider is large.

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Ron

hitwaterfish

Hi Ron,

I am now building a micro-EDM pulse generator. It needs a very short pulse width. I have got some high speed MOSFETs and MOSFET drivers recently. I want to test how high the frequency can be. So I need the signal source. I have use the LM567 before but I cann't use it here because it is not able to make the high frequency pulse. I have been looking for a efficient and low-cost way to build the signal source because I just want to do some experiment. I am not familiar with the NE564. I thought if I set the diveder ratio to N and the input frequency to F, the output frequcney would be N*F. So I could get different output frequencies. As you said, this way wouldn't work. Maybe I should choose some other way.

Thanks for the advice.
Thanks all.