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need help!

srcmt80

May 30, 2011
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not sure if this will even work, but i would like to put something together to control frequiency, and voltage, i need it to have a pulsating frequincy range of around 60hz to 200hz and also be adjustable from 1- 20 volts or so at 2 +/- 0.5amps with a dc current. any takers to help me with this. im still new to electronic, but im not green! so lets hear it people thanks. cant talk to much about what i have planned for this. but i will give creddit where it is do!
 

davenn

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Sep 5, 2009
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We are not green dummies either ;)

we want more than credit if we do the work for you !!
we want at least 50% of all earnings including ALL royalties for future use of "OUR" idea that "YOU" are using ! :)

do you really think people will design a money earning system for you for just a thankyou ? ;)

cheers
Dave
 

poor mystic

Apr 8, 2011
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Hi srcmt80
So, you want a variable power supply to provide up to 2.5A at between 1 and 20 V.
You also want the unit to be capable of providing DC instead of AC. Here's an idea for the AC part of your needs.
If you could be a bit clearer about your DC needs that'd help...

AC supply

You could use an audio amplifier and feed it a signal from your soundcard. The signal could be generated by Audacity and amplified just like any other signal. The amplifier would be called on for (20V x 2.5A = 50W) 50 Watts of continuous power, so I'd use a 100W musical instrument amp. I'd use my multimeter to test whether the load was getting the voltage I wanted.


I hope this works out for you, and I ask only for the usual 1% percent of the turnover from your invention, which I promise to spend encouraging creative individuals. Also, I will buy davenn a beer, and let him borrow my Learjet when I'm not using it.
 
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duke37

Jan 9, 2011
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Hi,
The requirement as I understand it is for a pulsating DC voltage with a frequency range of 60 p/s to 200 p/s with a variable voltage between 1 and 20V capable of a current up to 2.5A.
If this is so, I would suggest a variable voltage DC supply and a 555 timer and fet to switch this to the output. The on/off time ratio would need to be specified. Does the current need to be controlled?
 

srcmt80

May 30, 2011
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thank you

you have been very helpful, so pretty much if i add a 555 timer to a tattoo power supply. ishould get what i need!
 
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srcmt80

May 30, 2011
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not trying to be negative i just dont like wasting time readin unnessary stuff on forums cause some guy needs to put his two sence in!
 

Puno

Feb 25, 2011
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don't reckon that would be the best way to go what are you trying to achieve
 

srcmt80

May 30, 2011
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yeah doesnt work with my time table, if someone isnt willing to help whats the point
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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The problem is srcmt80, your description of requirements is not very clear and you have indicated an unwillingness to provide more details.

You may get some general hints, but don't expect anything specific when we can't actually tell what you need.

You could, for example, answer duke37's question.

And what do you mean by pulsating frequency? Do you mean you want the frequency to vary? Or do you mean that you want DC with an AC component imposed on top of it? Or do you want PWM, PPM, or some other form of pulsed DC?

And what do you want to vary? Modulation depth? Peak voltage? Frequency? Duty cycle?

And about the current -- Is it to be regulated,? Limited? load dependant?

And is the load Resistive? Capacitive? Inductive?

If you can't tell us what it is then you're going to have to be very specific about what you want and then run the risk that you'll get something less suited to your need than if you told us what it was for.

People here like to help, but they are not required to.

Also, I suspect English is your second language, so let me point out the following:

"im" --> "I'm"
"cant" --> "can't"
"where it is do" --> "where it is due"
"put his two sence in" --> "put his two cents in"
"doesnt work with my time table" --> "doesn't work with my timetable"
"isnt" --> "isn't"
 

srcmt80

May 30, 2011
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, 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. and no my only language is english! i appologize that its not up to snuff, i had a quite bothersome childhood, so wasnt able to complete further then the seventh grade. thanks for the grammer lesson!
 

srcmt80

May 30, 2011
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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!
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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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.
 

srcmt80

May 30, 2011
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for example, im lookin for something that i can set at say 100hz, then be able to adjust the strength of the eletromagnet, by the voltage without changing the already set frequancy, duty is around 50% and that will be adjustable by mechanical means. but only by +/= 20%, thanks you are being extremely helpfull, sincerely shawn
 

srcmt80

May 30, 2011
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also since the hertz frenquancy band is rather small only needing to change between 60-200hz. and the optimal volts for equipmant i plan on running will be between 5-12volt. on a 2amp set up. if that helps any!
 

Puno

Feb 25, 2011
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sounds like a pwr supply for a tattoo machine that is capable of supplying dc. and records the switching of the coils of the tattoo machine. if i am right check out the post under Electronics Projects titled Variable 0-15v dc supply.

If it is for a tattoo machine then the pwr supply should not be pulsating inorder to read out frequency it is the switching of the 2 coils on the machine that combined with some other circuitry, to be able to count the switching of the coils.

let me know if is for tatt. machine supply because i myself at the moment learning to be a tattoo artist.
 

srcmt80

May 30, 2011
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a tattoo machine is very much the base for the idea, being a certified artist thats what got me into electromagnetics, but no if it was for tattooing i wouldnt want a power supply that pulsates, i have very well running machines, and they all serve there purpuse, i have a power suplly that reads all my specs. it helps for so many other things! how long you been tattooing?
 

srcmt80

May 30, 2011
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so can i buy a PWM with that hz frenquancy, and just use it for a on/off switch for the power comming out of the supply, and where would i get one, or do i have to build it myself?
 

srcmt80

May 30, 2011
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so heres some other ways i was thinking off seeing if theres a possable way to get what im looking for, what do you think about these ways of controlling the frenquancy signal? Pulse-code modulation, pulse destiny modulation. pulse postion modulation. or maybe set up like a class D amplafier, my other thought is being able to switch various curcuits to various capcitors, then use the voltage created by the power supply to change the speed and and power to the electromagnets. does any any this sound reasonable, would one way be better then the other and why?
 

srcmt80

May 30, 2011
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several of those would have to be controlled digitaly i beleive. so i dont know how i would be able to apply
them exactly, and i assume that i would need a bunch of software!
 

(*steve*)

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so can i buy a PWM with that hz frenquancy, and just use it for a on/off switch for the power comming out of the supply, and where would i get one, or do i have to build it myself?

I guess you're going to have to design and build one yourself. I can't think of anything off-the-shelf that will work.

For the power supply, there are several options if you look at bench power supplies. An expensive option, but at least you don't have to build it yourself.

You will require an additional low power PSU to drive the 555 (presuming that is your choice) as the input voltage can vary below what the 555 will operate from. This could be a cheap wall-wart type of thing.

If you google "555 PWM" you should be able to find plenty of circuits.
 
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