Hi

I need either a square to sine wave convertor or a sine/triangle wave generator with variable frequency adjustment

The problem is the range needs to be about 0-2mhz if possible

The sine/triangle wave will be used with comparitors to generate a duty cycle to control 4 mosfets in a full bridge arrangement.

I want to use a sine/triangle wave as my timing mechanism because it will allow me to adjust the duty cycle of the mosfets by adjusting the reference voltage connected to the comparators.

The device is for the control of a small solid state tesla coil

the frequency range is large because I am unsure what the resonant frequency will be required

Does anyone know of a good way to generate a variable frequency sine wave?

 

buy a waveform generator - or build it.
What about googling first ? There're myriads of hobby projects covering wave generation, sines, and such stuff

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i² = j² = k² = ijk = -1

 

I have googled it, most wave generators seem to be limited to 100khz

 

try these for starters,50khz to 500khz,is the range you're looking for apparently..
http://users.pandora.be/educypedia/e...icitytesla.htm

 

he's not looking for teslacoils... he wants to build a sort of controller, which allows him to modify the coils frequency, i assume.

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i² = j² = k² = ijk = -1

 

the sine/triangle wave is to set the frequency that the mosfets switch at some tesla coils work on 4Mhz resonance.

I want a large frequency range because this controller may be used with several different coils

 

To convert a square wave to a sine wave, can't you just use a low pass filter? It will give you an approximate sine wave anyway, depending on the quality and complexity of the filter.

 

I believe that a 555 timer can kick out 2MHZ in a squarewave or triangle wave. and just add a lowpass filter like poopeater said.

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I'm no electronics god, i just talk too much.

 

how do you get a 555 to output a triangle wave

All I need i a triangle or sine wave, if a 555 can prioduce a triangle wave then that will solve my problem

do you have a circuit diagram for a 555 outputing a triagular wave, I've only been able to find 555s producing square and saw tothed waves

 

Maxim has a MAX038 function generator IC that has sine, square and triangle wave outputs up to 20MHz.

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Uncle $crooge

 

what kind of solid state TC are you building? Class E? Dual Resonant? off-line? Vac. Tube?
How small is small?

You dont need a freq. generator that runs in the high kHz range. You design the primary ckt. to resonate at the same frequency of your secondary. Then you just switch the primary circuit at about 100-1000Hz (commonly referred to the break rate). This may change based on the type of SSTC you're building, but this is how the off-line TC operates.

I'm currently building an off-line TC.
The igbt and cap bank: http://www.personal.psu.edu/jrz126/i...d_cap_bank.JPG
The secondary: (12" dia by 35"h) http://www.personal.psu.edu/jrz126/i...sm_topload.JPG

Take a look at www.4hv.org, and Steve Conner's site: www.scopeboy.com

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Jeff
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.

 

It will be a dc solid state tesla coil with 4 mosfets in a full bridge arrangement
similar to this one
http://users.tkk.fi/~jwagner/tesla/S...simplified.gif

my controller circuity once finalised will be something like this
http://i73.photobucket.com/albums/i2...53/diagram.gif

Is there a way of calcularting the resonant frequencys before buildning the coils?

 

A low pass filter will only work with a small frequency range.

I've done a Google search and this I can find.

Here are some other interesting links:
http://hem.bredband.net/bersyn/VCO/vco_complex.htm
http://mypeoplepc.com/members/scottn...ynth/id20.html

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I also post at the following sites:
http://www.stop-microsoft.org http://www.heated-debates.com
Screen name: Aloone_Jonez
And http://www.silicontronics.com, same screen name as here.

 

I've found a ressonance calculator and the ressonance of the coil I intend to build is around 20khz so If I can find a wave generator at about that frequency then I am set

edit: could I just add an integration circuit onto a 555 timer circuit to convert the square wave to a triangle wave?

 

Looks like a Dual Resonant design. I think you'll want to go with a PLL (phase locked loop) design. I'm not too familar with the DRSSTC design, but they can be quite complicated. Steve Ward has some good info...http://stevehv.4hv.org/drsstc_design.htm

What are the specs of your coil/topload? 20 khz seems kinda low. My 12"X35" coil will resonate at about 40-50khz. What are the specs on your mosfets?

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Jeff
To the optimist, the glass is half full.
To the pessimist, the glass is half empty.
To the engineer, the glass is twice as big as it needs to be.