my only language is english!
OK, sorry. We do get a number people here who don't have English as a first language.
, i need to put some thing together that is capible of varing the hz and the voltage at the same time, need to be able to set it to desired hertz, and keep that steady while i can increase the voltage for more power to eletromagnets, amost like a tattoo machine, dose that help any.
pretty much im looking for the best way to combine a DC pulse width modulater to a adjustable power supply! but i need a solid on/off curcuit, with no voltage in between my pulses!
OK, so you're powering electromagnets, that means an inductive load.
And you want pulsed DC. Presumably, a square wave output is what you want because you do say PWM. That means the output is essentially 0V or +V, where +V is your set voltage.
Now where things get confusing again is where you mention variable frequency and PWM. These are sort of opposite.
PWM typically has a fixed frequency where the duty cycle is adjusted.
Variable frequency suggests a fixed (probably 50% duty cycle) and variable frequency.
If it's to power an electromagnet, Are you hoping it will "pull in" with each pulse? If so, are you trying to vary the proportion of time the device is active. the rate at which it activates, or a combination of both?
Essentially I see the device you want being a variable DC power supply capable of the range of voltages you're interested, followed by a circuit (for simplicity let's say based on a 555) that turns the output on and off as desired. This circuit would have to be powered by something other than the output of your variable power supply, so you'd need a separate small regulated supply for it.
Because you're powering an inductive load, the current will lag the voltage and you will need a flyback diode across the output to prevent the inductive spike induced at the end of each pulse from damaging you power supply.
The big unknown is what controls you want for the pulse generator. Ideally I guess different controls for frequency and duty cycle but this is non-trivial with a 555. Perhaps independently controllable mark and space timings would suffice?
This all still makes a number of assumptions, but hopefully it gives you some ideas.