12kHz oscillator cct anybody?

[Martin Peters]

Hello,

Any helpful soul out there able to point me to a schematic for a transistor
(or 1 chip) cct that'll deliver a fixed 12kHz output?

Thanks - Martin

 

[John Popelish]

Martin Peters wrote:

Hello,

Any helpful soul out there able to point me to a schematic for a transistor
(or 1 chip) cct that'll deliver a fixed 12kHz output?

Thanks - Martin


What waveform? How fixed?

 

[Martin Peters]

What waveform? How fixed?

Sorry - sine wave, and stable enough so that when it's mixed (with SA602)
with another signal which is then tuned with a radio in sideband mode, it
won't require retuning after warm-up. This more improtant than actual
accuracy of the 12kHz. 100Hz here or there not important.

Thanks - Martin

 

[Brian Howie]

--
--
Brian Howie
SELEX Sensors and Airborne Systems Ltd
Sensor Systems Division
Crewe Toll Phase II, 1st Floor,
Edinburgh EH5 2XS
Phone +44 (0)131 343 8769
FAX +44 (0)131 343 8941
Email brian.howie@baesystems.com

"Martin Peters" <martin.peters@ntlworld.com> wrote in message
news:HNQge.4483$f5.1259@newsfe6-win.ntli.net...

Hello,

Any helpful soul out there able to point me to a schematic for a
transistor
(or 1 chip) cct that'll deliver a fixed 12kHz output?

Thanks - Martin

I read the thread.

Use a Phase shift oscillator. DONT USE A 555.

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/oscphas.html

Brian

 

[colin]

"Martin Peters" <martin.peters@ntlworld.com> wrote in message
news:V5Yge.5018$hn5.3433@newsfe2-win.ntli.net...

What waveform? How fixed?

Sorry - sine wave, and stable enough so that when it's mixed (with SA602)
with another signal which is then tuned with a radio in sideband mode, it
won't require retuning after warm-up. This more improtant than actual
accuracy of the 12kHz. 100Hz here or there not important.

Thanks - Martin

in that case you probably need a crystal for stability, dividing it down to
12khz, the most comon nearest is 32khz but this doesnt divied into 12 very
well, you can get 'programable crystal oscilators', wich have internal
divide by n counters. you can use a filter to clean the squarewave into a
sinewave.

or maybe you have another crystal oscilator somewhere in your circuit you
can divide down ?

Colin =^.^=

 

[John Fields]

On Fri, 13 May 2005 06:49:25 GMT, "Martin Peters"
<martin.peters@ntlworld.com> wrote:

What waveform? How fixed?

Sorry - sine wave, and stable enough so that when it's mixed (with SA602)
with another signal which is then tuned with a radio in sideband mode, it
won't require retuning after warm-up. This more improtant than actual
accuracy of the 12kHz. 100Hz here or there not important.

---

HC4066 +5
+----------------------+ |
+--|MR | [100R]
| | | |
GND | RS RTC Q8 | +--[3.6nF]--[50mH]-->>--+
+-+------------+---+---+ | |
| | | C [100R]
+----[1M]----+ +--[1000R]---B 2N4401 |
| | E +--->>--+
| [500R] | |
| | GND GND
+---[XTAL]---+
| |
[10pF] [10pF]
| |
+------------+
|
GND

The 4066 is being used as an oscillator and a divider, with the
crystal frequency at 6.144 MHz. After being divided by 512, it exits
the counter as a 12kHz square wave and is then sent through a bandpass
filter to make the AC sine wave you need from it. I simulated it with
LTC's SWCADII, and the netlist follows.

The crystal is an Epson CA-301 6.1440M-C and the component values
arount it are from a design guide they have at:

http://www.eea.epson.com/go/Prod_Admin/Categories/EEA/QD/Crystals/mhzThruhole_Crystals/go/Resources/TECHNOTES/OSCDESIGNGUIDE

No guarantees, but it's a starting point!


Here's the netlist:

Version 4
SHEET 1 880 680
WIRE -224 432 -224 176
WIRE -224 560 -224 512
WIRE -224 592 -224 560
WIRE -80 432 -80 384
WIRE -80 560 -224 560
WIRE -80 560 -80 512
WIRE -64 176 -224 176
WIRE -32 384 -80 384
WIRE 80 384 48 384
WIRE 144 176 16 176
WIRE 144 336 144 176
WIRE 144 560 -80 560
WIRE 144 560 144 432
WIRE 208 176 144 176
WIRE 352 176 272 176
WIRE 352 240 352 176
WIRE 352 416 352 320
WIRE 352 560 144 560
WIRE 352 560 352 496
FLAG -224 592 0
SYMBOL voltage -224 416 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL npn 80 336 R0
SYMATTR InstName Q1
SYMATTR Value 2N4401
SYMBOL voltage -80 416 R0
WINDOW 3 -30 212 Left 0
WINDOW 123 -30 240 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value PULSE(0 5 0 0 0 4.167E-5 8.33E-5)
SYMBOL res 64 368 R90
WINDOW 0 -37 56 VBottom 0
WINDOW 3 -35 56 VTop 0
SYMATTR InstName R1
SYMATTR Value 1000
SYMBOL res 32 160 R90
SYMATTR InstName R2
SYMATTR Value 100
SYMBOL cap 272 160 R90
WINDOW 0 -18 -15 VBottom 0
WINDOW 3 -18 -20 VTop 0
SYMATTR InstName C1
SYMATTR Value 3.6E-9
SYMBOL ind 336 224 R0
WINDOW 0 -47 45 Left 0
WINDOW 3 -66 80 Left 0
SYMATTR InstName L1
SYMATTR Value 50E-3
SYMBOL res 336 400 R0
SYMATTR InstName R3
SYMATTR Value 100
TEXT -258 648 Left 0 !.tran 0 .005 .004 uic

--
John Fields
Professional Circuit Designer

 

[Dr Engelbert Buxbaum]

Martin Peters wrote:

Sorry - sine wave, and stable enough so that when it's mixed (with SA602)
with another signal which is then tuned with a radio in sideband mode, it
won't require retuning after warm-up. This more improtant than actual
accuracy of the 12kHz. 100Hz here or there not important.

Try a Wien-bridge oscillator build around an OpAmp, for 12 kHz even the
venerable 741 should work. Any book on basic OpAmp circuits should cover
this.

 

[Rich Grise]

On Tue, 17 May 2005 10:34:52 +0200, Dr Engelbert Buxbaum wrote:

Martin Peters wrote:

Sorry - sine wave, and stable enough so that when it's mixed (with
SA602) with another signal which is then tuned with a radio in sideband
mode, it won't require retuning after warm-up. This more improtant than
actual accuracy of the 12kHz. 100Hz here or there not important.

Try a Wien-bridge oscillator build around an OpAmp, for 12 kHz even the
venerable 741 should work. Any book on basic OpAmp circuits should cover
this.

Nah. If you're going to be screwing with tuned circuits anyway, then
use a crystal and divider chain, and a low-pass filter at its output.
You can use your opamps for the low-pass filter.

And where would you get a light bulb to use to stabilize a Wein bridge
at opamp power levels anyway?

Thanks,
Rich

 

[David Eather]

Rich Grise wrote:

On Tue, 17 May 2005 10:34:52 +0200, Dr Engelbert Buxbaum wrote:


Martin Peters wrote:


Sorry - sine wave, and stable enough so that when it's mixed (with
SA602) with another signal which is then tuned with a radio in sideband
mode, it won't require retuning after warm-up. This more improtant than
actual accuracy of the 12kHz. 100Hz here or there not important.

Try a Wien-bridge oscillator build around an OpAmp, for 12 kHz even the
venerable 741 should work. Any book on basic OpAmp circuits should cover
this.


Nah. If you're going to be screwing with tuned circuits anyway, then
use a crystal and divider chain, and a low-pass filter at its output.
You can use your opamps for the low-pass filter.

And where would you get a light bulb to use to stabilize a Wein bridge
at opamp power levels anyway?

Thanks,
Rich


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You use a J-Fet biased by the output(I skipped a few details) not a
light bulb for low power levels. It works beautifully ultra low
distortion and if you want low frequencies below 1 Hz.

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[Watson A.Name - \"Watt Su]

"David Eather" <eather@tpg.com.au> wrote in message
news:42BD3E2D.6080205@tpg.com.au...

Rich Grise wrote:
On Tue, 17 May 2005 10:34:52 +0200, Dr Engelbert Buxbaum wrote:

[snip]

And where would you get a light bulb to use to stabilize a Wein
bridge
at opamp power levels anyway?

Thanks,
Rich

IIRC, the opamp datasheet from more than one mfgr has a Wien Bridge Osc
in the apps section, and they usually use a 327 or other 28V .04A mini
or submini lamp. Sometimes I see a 1869 bayonet base used. I think a
possibly better one is the 12v .025A grain of rice lamps that Rat Snack
sells (or used to sell). In any case, if you search for a WBO, you'll
run across a number of them that use a lamp to stabilize the opamp.

This one uses diodes so it tends to add distortion.
http://www.ecircuitcenter.com/Circuits/opwien/opwien.htm

If you want very low distortion, use a lamp. Here's more info on all
types.
http://sound.westhost.com/project22.htm

And more info.
http://users.telenet.be/educypedia/electronics/analogosciltypes.htm

 

[Chris]

Martin Peters wrote:

Hello,

Any helpful soul out there able to point me to a schematic for a
transistor
(or 1 chip) cct that'll deliver a fixed 12kHz output?

Thanks - Martin

Take a look at the LM555.

http://www.uoguelph.ca/~antoon/gadgets/555/555.html

One 8-pin IC (commonly available for less than a buck), along with one
cap and two resistors. You can replace one of the resistors with a
resistor and a pot to tweak it in to value.

If this doesn't do the trick, possibly you might want to provide more
information:

For example: Sine, square, triangle, sawtooth? Logic level? How about
duty cycle? Does it have to be 50% duty cycle, or is that important?
Amplitude (voltage level)? How precisely do you have to hold the
frequency? What's the load (what are you connecting to this)?

Good luck
Chris