Muller Dynamo

[EMdevices]

@ redrichie


I just illustrated and explained the shorting in the other thread (for experimentalists.) 

Coil shorting happens automaticaly in RomeroUK's dynamo due to the use of diode bridges and an output capacitor, since conduction occurs only when the induced coil voltage rises above this cap voltage plus the voltage drop across the diodes.   These current pulses are very short and occur at the max voltage peaks.   

So, coil shorting at max voltage is quite common and not some exotic practice.   

If on the other hand you had a load resistor connected directly to a generator coil, then the current would flow into the load all the time and vary according to ohms law,  but in his dynamo,  current pulses flows quickly into the capacitor in short duration bursts, so the applicable load resistance while the current flows is the coil resistance of about 1 ohm.    (capacitors are efectively shorts for AC analysis)

EM

[e2matrix]

good question. I don't know. I have not spent too much time thinking about this yet. This was just my second run quick test to see if it would even spin. My first run test with relay was a total disaster and was running at less than 20rpm.

Those little coils made a gigantic difference. Now, the timing was a error and trial until I found a good spot. What was interesting to me is that longer pulses were worse and shorter were better. Resonance plays a big role where once you achieve it you can proportionality decrease the ON time duration (which is my case) and still improve things.

My setup is not taking the speed of the rotor into consideration so as faster it goes I am still at a constant ON time. I will eventually fix that on the code.

BTW, I think it is not 500 ms but 0.5 ms ON time or may be even 0.05ms. I have to check the code.

Fausto.

Is that an Arduino board I see in your video?  I assume you are using that for controlling the drive coil pulses?  Also is the big Weston analog Amp meter on the output side?  Nice setup you have plengo.  Looks like you've got all the tools to tune this in once it's complete. 

[minoly]

@ redrichie


I just illustrated and explained the shorting in the other thread (for experimentalists.) 

Coil shorting happens automaticaly in RomeroUK's dynamo due to the use of diode bridges and an output capacitor, since conduction occurs only when the induced coil voltage rises above this cap voltage plus the voltage drop across the diodes.   These current pulses are very short and occur at the max voltage peaks.   

So, coil shorting at max voltage is quite common and not some exotic practice.   

If on the other hand you had a load resistor connected directly to a generator coil, then the current would flow into the load all the time and vary according to ohms law,  but in his dynamo,  current pulses flows quickly into the capacitor in short duration bursts, so the applicable load resistance while the current flows is the coil resistance of about 1 ohm.    (capacitors are efectively shorts for AC analysis)

EM

Redrichie,
that's a nice find!
I've been playing around w/ what few AC caps I have on hand and they do short the coil and produce a higher voltage just by putting them in parallel w/ the coil before the FWBR. it also makes a difference what cap you have after the FWBR. I do not have enough on hand to optimize and produce a significant increase in speed, I will experiment w/ other coils to see if I have the right coil to cap combo on hand before making a trip to pick up more caps. this really feels like an LCR type action going on here.
Thanks for posting that

[e2matrix]

Redrichie,
that's a nice find!
I've been playing around w/ what few AC caps I have on hand and they do short the coil and produce a higher voltage just by putting them in parallel w/ the coil before the FWBR. it also makes a difference what cap you have after the FWBR. I do not have enough on hand to optimize and produce a significant increase in speed, I will experiment w/ other coils to see if I have the right coil to cap combo on hand before making a trip to pick up more caps. this really feels like an LCR type action going on here.
Thanks for posting that

minoly, I think you meant EMDevices as that was his post in response to redrichie's question on coil shorting.  No big thing just giving credit to EM for that info.  I actually didn't get the idea though from his post that you would put AC caps directly on the coil before the FWBR.  Sounds like you are onto something though with that.  What sort of value's have you tried in the AC caps? 

[konehead]

4tesla wrote:"
I was wondering what to use to drill large holes in acrylic.. would this hole saw work?..
http://www.sears.com/shc/s/p_10153_12605_00966287000P?sid=IDx20070921x00003a&ci_src=14110944&ci_sku=00966287000P

Thanks!"

I like using holes saws to cut out discs since you have perfect center hole and the disc will be perfectly round too...Just go slow and take your time dont dig in too deep all at once go with very light pressure

a very good trick when cutting through acryilc or lexan or polycarbonate etc plastics is to cool it down by splashing water on the plastic as you drill..just did this the other day cutting thorugh some very strong plexigas - I th ink it was polycarobnate type......this works good with acrylic too - keeps it from melting and also lubricates it too.
Be sure to CLAMP down the plastic being cut with Cclamps or whatever...
ABS plastic is good plastic to use since it accepts glue very well but it really likes to melt when its drilled and it oozes up all over theplace when you drill it out - for this stuff I will spray on some WD40 oil when drilling out discs with hole saws..
also when drilling smaller holes in plasticswith drill bits, its good to lube the bit too with some WD40 or whatever you want (water too) - it really helps - sometiimes the bit will jam in the platic or break off ruining everythign but the oil really helps prevent this.
Also notice the plastic sheets to cut rotors out of are never perfectly flat, and usually warped from sitting around in the store,  so running the sheet through a planer first a few times will make a very flat surfaced rotor..