12kHz oscillator cct anybody?

transistor

Take a look at the LM555.

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

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

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 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 snipped-for-privacy@baesystems.com

transistor

I read the thread.

Use a Phase shift oscillator. DONT USE A 555.

Brian

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 =^.^=

---

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:

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

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

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.

[snip]

bridge

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.

If you want very low distortion, use a lamp. Here's more info on all types.

And more info.