Oscillator
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Posts: 46,084
Alejandro-
As Duncan wrote a few days ago, "This sounds like the perfect job
for Steve Parkiss' Pulse Machine". He was talking about a different
task, but I think the comment is still valid. The Pulse Machine can
give you a precise, gated 40 or 38 KHz pulse stream and is designed
to be Stamp-friendly. Also has several other pulse functions and a
simple but effective LCD interface built in. < US$10 in parts.
Help yourself to the code (see web page below) and build your own or
we can talk off the list about a purchase if you like.
Regards,
Steve Parkis
http://home.earthlink.net/~parkiss/
On 30 May 00 at 17:48, Alejandro Vazquez wrote:
> I would like to generate a 40khz pulse,, I have 2
> options: 1) Using a timer 555 but it is too dificult
> to get a really good presicion.,, the other one is to
> use a IC with a cristal oscillator but the problem is
> that I dont know wich IC is a good one to use.
> If anyone know any IC that I can use with a Cristal
> please tell me!
As Duncan wrote a few days ago, "This sounds like the perfect job
for Steve Parkiss' Pulse Machine". He was talking about a different
task, but I think the comment is still valid. The Pulse Machine can
give you a precise, gated 40 or 38 KHz pulse stream and is designed
to be Stamp-friendly. Also has several other pulse functions and a
simple but effective LCD interface built in. < US$10 in parts.
Help yourself to the code (see web page below) and build your own or
we can talk off the list about a purchase if you like.
Regards,
Steve Parkis
http://home.earthlink.net/~parkiss/
On 30 May 00 at 17:48, Alejandro Vazquez wrote:
> I would like to generate a 40khz pulse,, I have 2
> options: 1) Using a timer 555 but it is too dificult
> to get a really good presicion.,, the other one is to
> use a IC with a cristal oscillator but the problem is
> that I dont know wich IC is a good one to use.
> If anyone know any IC that I can use with a Cristal
> please tell me!
Comments
options: 1) Using a timer 555 but it is too dificult
to get a really good presicion.,, the other one is to
use a IC with a cristal oscillator but the problem is
that I dont know wich IC is a good one to use.
If anyone know any IC that I can use with a Cristal
please tell me!
Best Regards
Alejandro Vazquez
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resistor between the input and output. Put a parallel cut crystal across the
input and output also. If the crystal is, for example, a 20pF unit, put a
20pF cap from the input to ground and another from the output to ground. Use
another section of the inverter to make the output square (you did say
pulse).
Could probably get away with a 74C or 74HC inverter but I haven't tried it.
You could also use any other inverting CMOS gate. For example, use a NAND
gate if you have one and tie the two inputs together to make 1 input.
Regards,
Al Williams
AWC
*NEW: PAK-VIII generates 8 channels of pulse output.
http://www.al-williams.com/awce/pak8.htm
>
Original Message
> From: Alejandro Vazquez [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=PILN1-aFqwZJB_67cq05rkwN9K0-XV8G0ZrDdQjeiln0mULU4k_AvSfGaciPbps3CLZcEcK-USLrHqXCqxMKYQ]alexvazquez@y...[/url
> Sent: Tuesday, May 30, 2000 7:49 PM
> To: basicstamps@egroups.com
> Subject: [noparse][[/noparse]basicstamps] Oscillator
>
>
> I would like to generate a 40khz pulse,, I have 2
> options: 1) Using a timer 555 but it is too dificult
> to get a really good presicion.,, the other one is to
> use a IC with a cristal oscillator but the problem is
> that I dont know wich IC is a good one to use.
> If anyone know any IC that I can use with a Cristal
> please tell me!
>
> Best Regards
> Alejandro Vazquez
>
> __________________________________________________
> Do You Yahoo!?
> Send instant messages & get email alerts with Yahoo! Messenger.
> http://im.yahoo.com/
>
>
go from a TTL osc at 40 mhz times 2 and then times3 and then times 2
again. Can it be done I wonder. I've seen some frequency dividers
used digitally. Or, is it better to go with the multipliers?
If you can help here I'd really be thankfull. Otherwise I'm using a
stamp to try and design an Alt-Azimuth head for the small dish.
Thanks Jim
The most common frequency multiplier is a PLL. At those frequencies, you
will need fairly exotic PLL chips (or discrete circuits). Some vendors that
come to mind: Maxim, Analog Devices, National (Comlinear products), and ICS.
You might be able to use a rate multiplier IC, if you can find one that
runs fast enough. Try to find a spec for something like '74AC97' or
'74AC167'. It's possible that you would have better luck searching on 'VHC'
or 'F' instead of 'AC'. Be aware that these chips work by selectively
dividing a higher-frequency master clock input, and they produce output
pulses that are not evenly spaced...
>Anyone know how to use digital means to increase frequency. I want to
>go from a TTL osc at 40 mhz times 2 and then times3 and then times 2
>again. Can it be done I wonder. I've seen some frequency dividers
>used digitally. Or, is it better to go with the multipliers?
>If you can help here I'd really be thankfull. Otherwise I'm using a
>stamp to try and design an Alt-Azimuth head for the small dish.
Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
Manufacturer of the famous BOB-II Serial Video Text Display Module!
I forgot to mention a sleazy tactic that can be used to double frequency
cheaply: Just connect your clock signal to both inputs of an XOR gate, but
delay one input with a simple R/C network (the series resistor alone is
sufficient at high frequencies). If you get the delay right, the gate
output will be 2X your input frequency.
>Anyone know how to use digital means to increase frequency. I want to
>go from a TTL osc at 40 mhz times 2 and then times3 and then times 2
>again. Can it be done I wonder. I've seen some frequency dividers
>used digitally. Or, is it better to go with the multipliers?
>If you can help here I'd really be thankfull. Otherwise I'm using a
>stamp to try and design an Alt-Azimuth head for the small dish.
Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
Manufacturer of the famous BOB-II Serial Video Text Display Module!