EVR microBrute / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

EVR microBrute

1 2 next

Move Thread

LAN_403

PhilGood

Fri Feb 17 2012, 04:36PM

Registered Member #3806 Joined: Sat Apr 02 2011, 09:20PM
Location: France
Posts: 259

Has anyone built the EVR microBrute yet ?

I'm planning to build it as my first TC and I'm interested in your opinions and advices about it ...

Thanks :)

jlr134

Sun Feb 19 2012, 04:55PM

Registered Member #3056 Joined: Mon Aug 02 2010, 01:24PM
Location:
Posts: 21

I get 18" from mine and Im not thru trying to squeeze a little more out of it.Assembly is step by step and Daniel walks you thru it real good, all you have to do is take your time and follow instructions. ( and when I needed help ..he was right there- I messed up the resonator first time) He uses good quality material and pcb. I think the only thing you supply is a fan and an enclosure.( I used a plexiglass enclosure.looks nice but not too easy to drill) I think its a real nice kit ( be warned while there is a circuit description, the basic theory of these devices are not covered. No big..there are so many online resources to pick that up , and this is the best one.)
I didnt use his torrid, I used a spun torrid so I had to change the primary turns to compensate for the frequency change in the secondary but i did that because this is my second coil and I wanted to see if I could , But there was no valid reason to change torrid and as a first kit I would advise against it because he has all the calculations done already based on his component values. If you follow his instructions, all you have to do is tweek the primary a little at the end. If you vary from his instructions, component values change, calculations will be off and you will have trouble.Its a great kit, not hard to build and an excellent introduction to the sport.

PhilGood

Tue Feb 21 2012, 04:27AM

Registered Member #3806 Joined: Sat Apr 02 2011, 09:20PM
Location: France
Posts: 259

Thanks jlr134 for your detailed answer, I just ordered the kit :)

Congrats on the 18", quite impressive for such a small coil ^^

I have carefully read the full PDF instruction manual and it is indeed very well explained - Which is a good thing for my first TC.

I also ordered Dan's book for the DRSSTC theory.

Do you have any pic of your coil, and especially close view of the enclosure ?
I am thinking to plexiglass too, and I'd be interested to see how yours looks like ;)

I'm also thinking to some improvement for easier power-on/off, my idea is to add:
- a rotary switch with 5 positions in the controler box, with 1:OFF, 2:Fan ON, 3:controler ON, 4:control power ON, 5:main power ON
- this switch would control relays located in the TC base
- a 12VDC switching power supply located in the TC base too would feed the relays, the fan, and the controler.
This way I would have only a single mains connection to the TC and no need for battery for the controler.

I'm only worried about possible EMI going through the cables to the controler, but maybe good filtering and shielding would avoid any problem.

Anyway, I will not try this until everything works fine the "normal way".

PhilGood

Wed Feb 22 2012, 08:28AM

Registered Member #3806 Joined: Sat Apr 02 2011, 09:20PM
Location: France
Posts: 259

I just received the 230V -> 115V 1KW transformer

jlr134

Wed Feb 22 2012, 11:53PM

Registered Member #3056 Joined: Mon Aug 02 2010, 01:24PM
Location:
Posts: 21

I thought about 12vdc fans, they dont push nearly enough air.I used a plexiglass football display case from ebay and with a dremel and a step bit it wasnt bad to work with.The problem was the top cracked under the weight of the resonator/topload It cracks easy when your drilling it. ( I reinforced it with a plexiglass circle cutout and weldon- youd never know.) The coil is at work and Im off this week but when I get back Ill try and remember to send you a few photos if you wish.
( I used coax for my controller cable, next time Ill go fiber optic.)
My suggestion to you would be definitively to build the kit as in the instructions first, tune it and get a feel for it and then plan and make your modifications .Also there are easier ways to have a single power connection to the device.And as a first coil builder, give some thought to winding the resonator. maybe even get some ebay wire and a piece of pvc and pratice before you do the actual (I made a coil winging rig)

PhilGood

Sun Feb 26 2012, 02:10AM

Registered Member #3806 Joined: Sat Apr 02 2011, 09:20PM
Location: France
Posts: 259

Thanks jlr134 for your detailed answer :)

Got it for the fan.

Maybe the plexiglass of your display case was too thin ? My plan is not to make a full enclosure but just have two 10mm thick plexiglass plates with 1" plexiglass cylindrical braces.

Of course before doing any modification I will build, run and tune the kit as instructed.

what would you suggest to have a single power cord, and do you have any link about fiber optic connections ?

I'm also thinking to build some kind of winding machine, what do you think is a correct turns/minute value?

And yes, some pics of your coil, (and especially close view of the enclosure) would be much appreciated ;)

Thanks again for your help :)

jlr134

Sun Feb 26 2012, 03:35AM

Registered Member #3056 Joined: Mon Aug 02 2010, 01:24PM
Location:
Posts: 21

The winder I used was made with a parallax stamp , a continuous servo and tank treads from one of their robot mod kits( belt driven).I have since made a better one based on this,.. .

Its direct drive and much better than what I had.If you forget the counter and get around using the pulleys...you can build this cheap ( providing your not going for a museum piece)
You will want it variable speed ,run as fast as you are comfortable with while maintaining even wire tension and of course no overlapped windings.Ive seen videos where these things are flying, I cant run it that fast and make a decent product..There is no correct turns/minute value.You will have to find your own speed.Hope that makes sense.The diameter of the coil is a factor . I just did a 4 inch diameter resonator and I think I was almost 1 turn per sec but dont think speed, think quality.

As for power I ran a single 120vac circuit into a terminal block and from there split it into three fused circuits. One for the fans( which are always on if the unit is powered) One feeds a spst switch and that feeds a 1 amp fuse and that feeds the low voltage transformer.Thats your control circuit The other circuit feeds a spst switch which feeds a 5 amp fuse that feeds the 120vac primary power input.Thats your power circuit.So one plug,three circuits, two switches,easy to power up or down in correct sequence.( make sure switches are properly current rated}

When you see my case , you'll see why it cracked, its hard to describe.But my size and yours are about the same.I basically stressed an area that had holes drilled too close together.As far as fiber optics, using the search function of this site will provide all the answers to your questions.I cant think of a better source of information.

PhilGood

Sun Feb 26 2012, 03:43PM

Registered Member #3806 Joined: Sat Apr 02 2011, 09:20PM
Location: France
Posts: 259

Hi Jlr :)

In a general way my plans are very close to what you suggest !

For the winding machine I was planning to use a motor with around 100:1 gearbox and variable speed around 1 turn/second. I was planning to use a sewing machine pedal to control the speed, but I think an on/off pedal and a potentometer for the speed are better. I think the turn counter is useless, but it's not too expensive so maybe I'll add it just for fun. I am also planning to use two conical hard rubber pieces instead of the pulleys. They would allow an easy and fast centering of any size PVC pipe. Now I just gotta find out if they exists, lol. I will also add a second rod, parallel to the main one and at a good distance (more than 50 cm), to hold the copper wire spool. I'm still a bit unsure about rod,bearings and flex coupler mouting, gotta think to it...

Powering : your solution is very close to my first idea ! The only difference is I will use relays instead of the spst switches. it's not even a matter of safety, but rather of logic. I consider the controller box's purpose is to operate the TC from distance, all commands should be on that box and there should be none on the TC itself. (+ my solution avoids the use of a 9V battery for the controller).

Fans : You used more than one (probly two). I'm curious to see what size they are and where you put them. I'm still a bit unsure about the fan(s) and their mounting, there are so many possible solutions... gotta think to that too... Just curious, what is your fan's airflow (in CFM) ?

I have a very nice 12V fan, 22cm diameter, It's rather silent with its 600 RPM speed, I could just put it above the PCB. It has a 95 CFM airflow, I wonder if that's enough (but Dan told me any muffin fan will do the job, but I have seen many "muffin" fans have a lower airflow, down to 30 CFM, the highest ones are around 120 CFM). Anyway, I can always try this with a temperature sensor on the heatsink and see how it goes...

I gotta admit that I didn't searched for fiber optic topics, I was too busy with more urgent things... (I moved a few years ago, and I gave to my friends or sold most of my tools, so it's like I'm starting from scratch). I'll have a close look to the fiber optic option soon.

One last question : I found some 2cm width copper foil tape with conductive adhesive. I would prefer that rather than aluminium, for the look. I wonder if there could be any inconvenience.

Thanks again jlr134 for posting all these detailed answers and suggestions, that really helps !

Edit: ok, I just plugged in my 12V 22cm fan, and I could barely feel the airflow. I really doubt it's anything near 95 CFM. Something is wrong with this fan specs. I'm gonna buy one or two of those 115VAC muffin fans.

PhilGood

Sat Mar 10 2012, 01:13AM

Registered Member #3806 Joined: Sat Apr 02 2011, 09:20PM
Location: France
Posts: 259

I just received my MU2A1 Muffin Fan

Indeed, it blows a lot more air than any 12V fan (even those rated with a high CFM)

And it's rather silent ... impressive !

Mu2a1 10

PhilGood

Wed Mar 21 2012, 11:12PM

Registered Member #3806 Joined: Sat Apr 02 2011, 09:20PM
Location: France
Posts: 259

I just received my microBrute kit :)

Packaging was very well done.

Here are the kit parts :

PCB is really high quality
(on top left, the modulator kit)

1 2 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob