So I am trying to work out some things with inductive coupling for the wireless transmission of power. I have 2 coils professionally made of known inductance(~326 uH), as I am novice at this I was not aware that a DC square wave would not create the desired effect and that I need a AC square wave. I have been lead to believe that the PWM on an arduino can double as an DC square wave generator. I have read that I may need a DC to AC inverter. Can this be built cost effectively by a novice such as myself?
This forum has helped me so much and I just want to say to all the dedicated administrators out there, you guys rock, this community rocks, arduino rocks, and open source rocks!
I am a business level developer making my first forays into EE, so all you EE guys out there take it easy on the idiot developer
Yes, arduino can output a squarewave that will end up looking ac-ish going thru a transformer - that's how DC/DC converters work.
At the same time, power in = power out. 20mA @ 5V is not much power.
What you really need is for the arduino to control a transistor which then switches much larger current into a transformer, to be output as power on the secondary side.
How much power are you trying to transmit?
TimmyCNinja:
So I am trying to work out some things with inductive coupling for the wireless transmission of power. I have 2 coils professionally made of known inductance(~326 uH), as I am novice at this I was not aware that a DC square wave would not create the desired effect and that I need a AC square wave. I have been lead to believe that the PWM on an arduino can double as an DC square wave generator. I have read that I may need a DC to AC inverter. Can this be built cost effectively by a novice such as myself?
This forum has helped me so much and I just want to say to all the dedicated administrators out there, you guys rock, this community rocks, arduino rocks, and open source rocks!
I am a business level developer making my first forays into EE, so all you EE guys out there take it easy on the idiot developer
A DC square wave will drive an inductor, creating the changing magnetic field needed to be coupled to a secondary inductor winding. A spark coil in a car works fine on pulsating DC input. More importantly you need to give a better picture of how much energy/wattage you wish to try and transfer and the maxium physical seperation from your winding coils. Trying to couple significant wattage using air coupling is very difficult, that is why power transformers mostly use iron cores and very close physical coupling of the windings. So tell us what loads your will be trying to power via this method and how much voltage and current it requires.
I have been lead to believe that the PWM on an arduino can double as an DC square wave generator. I have read that I may need a DC to AC inverter. Can this be built cost effectively by a novice such as myself?
The answer will depend on your coil construction. If your coil has a center tap, or one can be easily added, you can use it. Otherwise, you will need a H-bridge to drive it.
it will need to be converted back to DC at the other end, we are looking for rough 4V with as many mA as we can get up to an amp, max distance 1cm. But just making an LED light up or getting the multimeter to jiggle would be enough to make me crap rainbows right now. Been at it for a bit.
That's actually fairly simple. Using your arduino to drive a switch single-ended.
just making an LED light up or getting the multimeter to jiggle
That's too easy: just route out the clock on a pin and connect it to your coil. Put another coil next to it, with a led connected to it and that led will light up.
I have been lead to believe that the PWM on an arduino can double as an DC square wave generator. I have read that I may need a DC to AC inverter. Can this be built cost effectively by a novice such as myself?
The answer will depend on your coil construction. If your coil has a center tap, or one can be easily added, you can use it. Otherwise, you will need a H-bridge to drive it.
Either way, your arduino can be useful.
Are you saying that simple DC on/off switching won't work? Because my example of a auto spark plug transformer seems to say it can work. I'm stating that one doesn't require AC only voltage switching to drive a transformer, switching DC works also.
You do not want to run a dc current through a coil. That's not a problem fortunately at low current / energy levels. You will see a SE configured dc converter for maybe 80-120w max.
After that, it is usually a bridged configuration (half bridge or h-bridge) so the coil sees ac.
You do not want to run a dc current through a coil. That's not a problem fortunately at low current / energy levels. You will see a SE configured dc converter for maybe 80-120w max.
After that, it is usually a bridged configuration (half bridge or h-bridge) so the coil sees ac.
I agree, and is why I asked the OP what his power transfer expectations/requirements were. I was mostly trying to deal with his question/statement:
as I am novice at this I was not aware that a DC square wave would not create the desired effect and that I need a AC square wave. and later:
I have been lead to believe that the PWM on an arduino can double as an DC square wave generator. I have read that I may need a DC to AC inverter.
And my response was that switched on/off DC can be used to couple energy through a transformer, it's done in many applications.
So I have been informed by my boss that you can apparently create the necessary signal with a 555 timer(squaring the output wave), and then just tune the receiver coil to your 555 frequency. Does that sound right everyone? BTW thanks to everyone so far who has posted, sometimes its hard to figure out how to even phrase the question when you dont know all the jargon and go to tricks of the trade.
TimmyCNinja:
So I have been informed by my boss that you can apparently create the necessary signal with a 555 timer(squaring the output wave), and then just tune the receiver coil to your 555 frequency. Does that sound right everyone?
Yes, as I said a switched DC square wave can pass energy through a transfomer, but again you have not answered more basic questions of the amount of energy in wattage you require for your application. All you have stated is the inductive values of the two windings you propose to use, not the winding current limits, not the switching frequency, not the air gap distance between the windings and again not how much power you need to transfer. You do not yet have enough information to proceed with your project/application.
it will need to be converted back to DC at the other end, we are looking for rough 4V with as many mA as we can get up to an amp, max distance 1cm. But just making an LED light up or getting the multimeter to jiggle would be enough to make me crap rainbows right now. Been at it for a bit.
I thought that was enough, I also mentioned just now that I dont know all the jargon, so switching frequency is as meaningless to me as say the term "rhizomorphic growth" would be to anyone who hasn't studied mycology. So if I don't respond with some expected value feel free to baby talk me, because I am not likely to grok what you are saying.
two questions, how do i post a new question and how do i stop a spark generator controlled from ATTINY 2313 from crashing the chip?
2313 o/p is opto isolated to a medium power transistor which switches a relay which powers a 555 which switches a large power transistor which drives a 12 car ignition coil.
its a MIDI app for a flaming pipe organ. i need to develop an arduino based board for each tube that listens for note or program midi messages and switches valves and this spark generator accordingly
to simplify i am using the blink sketch on the 2313 and i get about 4 or 5 nice sparks and then it stops.
previously when using the midi in to trigger the o/p the spark has also crashed parts of the music hardware
apologies for tagging onto the bottom of this post and thanks in advance for any help
I'd start by making sure that there was no electrical connection between the ignition circuit and the electronics. Since you have a relay, that would seem a natural way to isolate them - but if you have used a common ground, common power supply or linked the two sides together any other way, you've defeated that isolation.
Then I would put the electronics in a grounded project box.
If it still suffers from electrical interference with no electrical connection and an RF shielded box, there's something very strange going on.