Searching \ for ' Buffer to drive T1CLK at 5.5Mhz from 1.2' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=buffer+drive+t1clk
Search entire site for: 'Buffer to drive T1CLK at 5.5Mhz from 1.2'.

No exact or substring matches. trying for part
PICList Thread
'[EE]: Buffer to drive T1CLK at 5.5Mhz from 1.2v pk'
2002\01\14@121038 by Peter Onion

flavicon
face
Sorry for the repost, typo in subject !

Folks,

I have a need to drive the timer1 clock input at 5-5.5Mhz from a lowish
impedance source of about 1.2v pk-pk.

Currently I have a discrete amplifier (which seems to take excessive current)
but I would prefere an IC device of some sort.

Any personal preferencies for a suitable (easily sourced in the UK) device ?

Peter.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\01\14@132041 by Martin Peach

flavicon
face
----- Original Message -----
From: "Peter Onion" <spam_OUTponionTakeThisOuTspamSRD.BT.CO.UK>
To: <.....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU>
Sent: Monday, January 14, 2002 12:14 PM
Subject: [EE]: Buffer to drive T1CLK at 5.5Mhz from 1.2v pk-pk source


> Sorry for the repost, typo in subject !
>
> Folks,
>
> I have a need to drive the timer1 clock input at 5-5.5Mhz from a lowish
> impedance source of about 1.2v pk-pk.
>
> Currently I have a discrete amplifier (which seems to take excessive
current)
> but I would prefere an IC device of some sort.
>
> Any personal preferencies for a suitable (easily sourced in the UK) device
?

You could use a CMOS inverter (e.g. 74HC00) with the signal passing through
a capacitor into the first gate. Maybe you would need resistors to bias the
input. If the output of the first gate isn't square enough, send it through
some more gates. There are usually six in a package.

/\/\/\/*=Martin

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\01\14@133423 by Dave Dilatush

picon face
Peter Onion wrote...

>I have a need to drive the timer1 clock input at 5-5.5Mhz from a lowish
>impedance source of about 1.2v pk-pk.
>
>Currently I have a discrete amplifier (which seems to take excessive current)
>but I would prefere an IC device of some sort.
>
>Any personal preferencies for a suitable (easily sourced in the UK) device ?

You could try a fast comparator IC such as National's LM361 or Linear
Technology's LT1394; but fast comparators are rather pricey (roughly
US$3.50 in singles at Digi-Key, for example).

If you'd like, you can post the schematic for your discrete amplifier;
I'd be willing to have a go at fine-tuning it for lower power
consumption if you want.

Dave Dilatush

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\01\14@141535 by Peter Onion

flavicon
face
On 14-Jan-02 Martin Peach wrote:

> You could use a CMOS inverter (e.g. 74HC00) with the signal passing through
> a capacitor into the first gate. Maybe you would need resistors to bias the
> input. If the output of the first gate isn't square enough, send it through
> some more gates. There are usually six in a package.

Ah, I didn't think of that sort of thing, but...

I just checked the values for Vih and Vil , and I don't think I've got enough
of a swing (even with it biased at half Vcc) to meet the spec.

However..

I could get a bit more drive from the oscilator (upto about 2v pk-pk I think)
and increase the attenuation on the input to the mixer by a suitable amount...

And...

I have got a couple of spare 74HC14 gates (schmitt trigger) which would be
better bet I think...

Thanks, I'l try it and see how it looks...

Peter.

----------------------------------
E-Mail: Peter Onion <ponionspamKILLspamsrd.bt.co.uk>
Date: 14-Jan-02
Time: 18:50:19

This message was sent by XFMail
----------------------------------

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\01\15@031855 by Vasile Surducan

flavicon
face
I think the best ( and easiest way ) is to use a fast comparator and
compare the input signal with ground ( or with a simple reference if the
signal is unipolar ). A small positive reaction is required. I hope that
keeping constant the signal phase is not important... else could be
problems. Also a simple inverter ( one bipolar transistor ) could be
enough if you have almost a square wave input signal and no phase
variations problems.

Vasile

On Mon, 14 Jan 2002, Peter Onion wrote:

{Quote hidden}

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email .....listservKILLspamspam.....mitvma.mit.edu with SET PICList DIGEST in the body


2002\01\15@053257 by Peter Onion

flavicon
face
On 14-Jan-02 Peter Onion wrote:
{Quote hidden}

I tried this last night.  I needed a little bit more signal than was available
from the oscilator, so a single x2 stage infront of a 74HC14 was all that was
needed.  It works a treat !  Thanks for the idea Martin.

Infact it works too well !!!  While I'm trying techniques and ideas out on my
PIC development system (before starting the final hardware) the special
hardware (12 bit serial DAC and buffer & the oscilator buffer) are on the end
of a short length of ribbon cable connected to PORTC.  The nice fast edges on
the 5.5MHz signal from the 74HC14 output caused rather a lot of cross-talk onto
the DAC clock signal on the adjacent conductor.  DAC data was being corrupted
and the control voltage was jumping all over the place.  Short term solution is
a 100pF on the output of the 74HC14 to slow the edges down a bit.  In the final
hardware the connection from the 74HC14 to the PIC will NOT be via ribbon cable
:-)

Peter.

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email EraseMElistservspam_OUTspamTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body


2002\01\15@100632 by Roman Black

flavicon
face
Peter Onion wrote:
>
> On 14-Jan-02 Martin Peach wrote:
>
> > You could use a CMOS inverter (e.g. 74HC00) with the signal passing through
> > a capacitor into the first gate. Maybe you would need resistors to bias the
> > input. If the output of the first gate isn't square enough, send it through
> > some more gates. There are usually six in a package.
>
> Ah, I didn't think of that sort of thing, but...
>
> I just checked the values for Vih and Vil , and I don't think I've got enough
> of a swing (even with it biased at half Vcc) to meet the spec.


Peter, how complex is your discrete circuit?
Surely you can do this with one transistor and
2-3 resistors, 5MHz is not exactly fast. One
transistor can be reliably configured to give
10x gain and you already have 1 volt P/P you
said?
-Roman

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listservspamspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body


2002\01\16@051037 by Peter Onion

flavicon
face
On 15-Jan-02 Roman Black wrote:
>
> Peter, how complex is your discrete circuit?
> Surely you can do this with one transistor and
> 2-3 resistors, 5MHz is not exactly fast. One
> transistor can be reliably configured to give
> 10x gain and you already have 1 volt P/P you
> said?

It was overly complex due to me trying to get unnecessarily fast edges.
Martin Peach's idea of just using a 74HC gate is working well (with a x2
bipolar amp infront of it !).

Peter.


----------------------------------
E-Mail: Peter Onion <@spam@ponionKILLspamspamsrd.bt.co.uk>
Date: 16-Jan-02
Time: 10:00:10

This message was sent by XFMail
----------------------------------

--
http://www.piclist.com hint: To leave the PICList
KILLspampiclist-unsubscribe-requestKILLspamspammitvma.mit.edu


More... (looser matching)
- Last day of these posts
- In 2002 , 2003 only
- Today
- New search...