Right voltage output using TCXO

stef1777 · 9th October 2007, 07:41 PM

Hi Folk!

I've a question for clock's masters.

I've a TCXO with an output of 1.71v. I want to connect it to a device to replace a regular cristal. I've enclosed the scope signal if this can help.

What is the right resistor value to insert to have the right output voltage? In fact, I don't know what should be the right voltage.

Unfortunaly, I don't have the device schematic but the first chip in in the circuit is an HCU04.

Stephane

stef1777 · 9th October 2007, 08:54 PM

Sorry wrong screen shot.

mkliu · 10th October 2007, 08:36 PM

hello,

I am playing around with my VRDS-10 and moving onto mod the clock part. Can you do me a favour that forward the schematic to my mail box 8888po@gmail.com Merci!

stef1777 · 10th October 2007, 08:49 PM

Quote:

Originally posted by mkliu
hello,

I am playing around with my VRDS-10 and moving onto mod the clock part. Can you do me a favour that forward the schematic to my mail box 8888po@gmail.com Merci!

I've to look in my archives.

stef1777 · 10th October 2007, 08:50 PM

And the schematic for the question at the botton if someone have the answer. ;-)

yygomez · 11th October 2007, 01:36 AM

Hi Stephane,
Remove C69, C60, and Q3. feed the output of your TCXO to pin1 trough a 0,01uf cap capacitor. That should do it.
please note tha you have to keep the bias resistor r48 ( do not remove).
Jorge

mkliu · 11th October 2007, 02:21 AM

Quote:

Originally posted by stef1777

I've to look in my archives.

Great Thanks and very much appeciated your help!

stef1777 · 11th October 2007, 06:19 AM

Quote:

Originally posted by yygomez
Hi Stephane,
Remove C69, C60, and Q3. feed the output of your TCXO to pin1 trough a 0,01uf cap capacitor. That should do it.
please note tha you have to keep the bias resistor r48 ( do not remove).
Jorge

Curently, I've connected the TCXO using an 47R resistor and it work. What is the advantage to use an smal caps instead?

mkliu, I'v sent the files.

.

yygomez · 11th October 2007, 03:37 PM

in short answer, Your TCXO is 3.3v, the circuit is 5v. With the cap and the R48 1M biasing the 74HCU04 the circuit is going to trigger on the steepest part of the TCXO waveform which means less jitter.

mkliu · 12th October 2007, 04:30 PM

Quote:

Originally posted by stef1777

Curently, I've connected the TCXO using an 47R resistor and it work. What is the advantage to use an smal caps instead?

mkliu, I'v sent the files.

.

Got the file, it's very useful.....I just start putign a new TXCO in my vrds10.....

11th October 2007, 01:36 AM	#6
yygomez diyAudio Member Join Date: May 2007	Hi Stephane, Remove C69, C60, and Q3. feed the output of your TCXO to pin1 trough a 0,01uf cap capacitor. That should do it. please note tha you have to keep the bias resistor r48 ( do not remove). Jorge __________________ JG

11th October 2007, 03:37 PM	#9
yygomez diyAudio Member Join Date: May 2007	in short answer, Your TCXO is 3.3v, the circuit is 5v. With the cap and the R48 1M biasing the 74HCU04 the circuit is going to trigger on the steepest part of the TCXO waveform which means less jitter. __________________ JG

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10th October 2007, 08:36 PM	#3
mkliu diyAudio Member Join Date: Sep 2006	hello, I am playing around with my VRDS-10 and moving onto mod the clock part. Can you do me a favour that forward the schematic to my mail box 8888po@gmail.com Merci!

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