Major Pyro Frustration

[David DeCristoforo]

I made a pen using the plan shown here

http://www.fishcarver.com/images/burning%20instructions.PDF

Then I got a computer power supply and using this

http://www.lavieenbois.com/html/pyrograveur_eng.htm

I tapped the 12VDC outputs. I "jumpered "pins 14 and 15 and used 10 and 16 for the 12VDC. Works great. Made a cable and that works great too and I get 12VDC across the two end terminals of the pen. But as soon as I connect anything across the terminals, the PS cuts out. I have some wire from an old heater but I also tried several other wires just to see and no matter what I put in the terminals, the PS quits. I haven't got a clue how these things work and I'm flying by the seat of my pants here. Obviously, again I'm missing something. I have ordered some "proper" nichrome wire but it's not here yet. should not the wire get hot regardless? It seems like the direct short is just kicking the PS off. After a minute or to it will fire up again with no apparent harm done.

[Doug Wolf]

207106
Front with banana plugs and selector switch.

207107

Rear show posts to clip charger too.

207108

Cherry pens with JB weld to hold wire and banana plug on end of wire.

I tried the same thing as you are trying with about the same results. Finally went to Sears and bought a manual 12 volt charger and wired a dimmer switch in the 120 volt input. Works like a charm and I haven't looked back. Make sure the chargers is manual, the electronic ones won't work (You can't vary the input voltage) with a dimmer switch.

[Jeff Nicol]

David, Most newer PS's have an anti short circuit in them so as not to burn them up, this is why it cuts out. I use just the plain old transformer without anything else but the dimmer and it will work. I am still woking on an electronic circuit to control the 12v AC out, but time has been hard to come by and illness has zapped my energy levels as of late.

Good luck,

Jeff

[David DeCristoforo]

"...newer PS's have an anti short circuit ..."

This is not really a "newer" one. I ripped it out of a pretty old PC. But I guess it's too new! Five bucks down the tubes!

So a 120VAC/12VAC transformer will work? It doesn't have to output DC? Does it have to have a specific amp rating? Or watts? What about watts? This is not my area of expertise! Or does anyone know how to bypass the short circuit protector in the PS?

[Jim Underwood]

Gotta be some kind of circuit breaker in there that you could bypass. I haven't taken any of mine apart to see...

I'd be a little leary of tearing into one without doing some reading first. Some of these electronics have capacitors that store a pretty dangerous punch for quite some time. Of course that's usually for monitors, cameras, and microwaves...

[Jim Underwood]

Say Doug, on the 10 amp setting have you been able to get below the 8 amp level before it cuts out? I thought mine was a manual charger, but there's evidently something automatic about it...

[David DeCristoforo]

OK, how about something like this and a dimmer switch?

http://www.knobsandhardware.com/doorbell-chimes/heath-zenith-125c-wired-transformer-doorbell-chime-metal_g547182.html?af=1527&cse=1527&ctype=2&gclid=CLzqptHEjKsCFckaQgodVDsWwA

[Dennis Ford]

The voltages look right but the current rating of that transformer is too small .

[David DeCristoforo]

"The voltages look right but the current rating of that transformer is too small ."

OK. I'm gonna show my ignorance again but exactly what current rating would I need and how do I determine what the rating of the transformer is? I admit it, I come up short when it comes to electrical stuff. I need this explained in the most simplistic terms possible!

How about this one?

http://www.grainger.com/Grainger/MILJOCO-Transformer-5GUU3?cm_sp=IO-_-IDP-_-RR_VTV70300505&cm_vc=IDPRRZ1

or this one...

http://www.electronictransformer.com/hatr12.html

or this...

http://www.pondmerchant.com/home/pon/page_554/manual_12v_transformers_by_aquascape.html?rid=amaz on&utm_source=amazon&utm_medium=feed&utm_campaign=amazonfeed

Most of the transformers I see are talking about watts not amps. It's all greek to me. Is a 60 watt 120v to 12v transformer powerful enough. Like one for an outdoor lighting system?

[Rick Markham]

David, use a multi meter and see what the resistance of your wire is that you are using. If it is a very low Ohm (less than 2) for your signature, then the powersupply is probably thinking it is a short circuit. It's worth a shot. Chances are there is a PCB chip in the powersupply that shuts it down in case of a short. If you increase the Ohms of your resistance wires it may keep it from kicking off.

You have to remember when you use a wire with a low ohm rating, your drawing a ton of amps to do the work. Increasing the resistence may bring the amperage drawn down to what the powersupply considers a reasonable operating level.

[Rick Markham]

As an example if your signature is 2.0 ohms, then you have the equation 12v= 2.0(I) I is in amps so your current is 6amps drawn. a 5amp transformer won't do 6amps. If the reistance of your signature is 3.0 ohms then 12v=3.0(I) Now I= 4.0 amps. It's probably easier to figure out what you can use, by knowing what resistance your signature is, and finding the approximate amps drawn is.

Though I might be going about this entirely the wrong way... That happens alot :D

[Jon McElwain]

I'm with Rick.

The Nichrome wire is a very poor conductor, otherwise known as a resistor. It resists the flow of electrons and in doing so, it heats up. Chances are, the heater wire is from a 120v heater?? So it may not provide enough resistance at 12 volts.

When you wire in the Nichrome, it should all work just fine.

[Rick Markham]

I'm with Rick.

The Nichrome wire is a very poor conductor, otherwise known as a resistor. It resists the flow of electrons and in doing so, it heats up. Chances are, the heater wire is from a 120v heater?? So it may not provide enough resistance at 12 volts.

When you wire in the Nichrome, it should all work just fine.

You either need to increase the length of the resistance wire used to increase the resistance, or go with a thinner gauge nichrome, with a known resistance per foot. A multi-meter will get you an exact reading. Being that the heating element is from a heater it is probably faily low Ohm/foot. A thinner Nichrome wire will provide a much higher resistance per foot. You're on the right track David, just wait for your Nichrome to show up ;)

[Kerry Burton]

David, don't give up on the computer power supply just yet. I haven't messed with them myself, but your description reminded me of something I learned from one of the Stu's Dungeon pages.

While trying to "upgrade" his electrolysis method for cleaning up parts of an old drill press (see http://www.ablett.jp/workshop/drill_press.htm ... search for "computer"), Stu noted less-than-ideal performance from his PC power supply. Then...

[Stu Ablett: OK, I finally figured out, that I needed a "load" on one of the 5Vdc lines to make the power supply come to life.]


This is actually mentioned obliquely on the page you linked to, but in the Adjustable Output section:

PSU usually don't like to have this kind of switching load, the regulation gets crazy. So you need to add a permanent load on the 5V line, say 100 ohms.


Hope this helps! :)

[John Lifer]

Absolutely, you HAVE to have a load on a lot of these supplies. Put you another small fan or something like that in place.


David, don't give up on the computer power supply just yet. I haven't messed with them myself, but your description reminded me of something I learned from one of the Stu's Dungeon pages.

While trying to "upgrade" his electrolysis method for cleaning up parts of an old drill press (see http://www.ablett.jp/workshop/drill_press.htm ... search for "computer"), Stu noted less-than-ideal performance from his PC power supply. Then...

[Stu Ablett: OK, I finally figured out, that I needed a "load" on one of the 5Vdc lines to make the power supply come to life.]


This is actually mentioned obliquely on the page you linked to, but in the Adjustable Output section:

PSU usually don't like to have this kind of switching load, the regulation gets crazy. So you need to add a permanent load on the 5V line, say 100 ohms.


Hope this helps! :)

[Thom Sturgill]

Dave, it sounds like you are using the 12V output, the article you linked to in the first post said:

You can connect your tip to 5V (or 3.3V) and GND. if it doesn't get too hot, that's it. otherwise, you need to find a mechanism to adjust the power.

The variable control also shows connecting the tip to the 5V line.

[Tim Rinehart]

David,
I'm about as frugal as they get...and I looked into the making of a system. Yea, if you have alot of the parts just laying around, you can Mcgiver a system together. If you don't...and aren't confident in what's needed to get results and not cause a problem later...try looking for a nice used model on CL or fleabay.
There is currently a nice used Saber Detail master on there now...currently at about $40 and change, I'm sure it will go up, but it's what I use and was recommended to me by someone who burns alot. I got mine off fleabay for about $70 plus alot of tips which aren't cheap. I couldn't be happier with the Saber system.
Another good make to find used is the Razertip kit. I'd say equally good from what I've heard.

[Doug Wolf]

Jim, I am usually at between 10 and 12 on the meter when I burn. The needle is right on the red/green dividing line. My only problem with I've had with my system was when the black clip-to-wire connection on the charger melted. I had the dimmer cranked all the way up and the tip wasn't even getting hot enough to burn. Then I saw the smoke coming from the back and discovered all my heat was going to the poor connection Sears had made when they crimped the wire to the clip. I just soldered it back together and it has worked fine since.

I looked at the picture of your charger and it looks like a manual one. If it's cutting out it should be cutting out on overload, not 8 amps but more like 12+.

[Dan Hintz]

Lots of good advice so far, though I only read in passing.

Be aware, there are multiple types of Nichrome wire (i.e., multiple resistance per foot values), and the resistance of Nichrome is orders of magnitude higher than standard copper wire. You need that higher resistance, otherwise, it's practically a dead short you're supply across the output.

[Chris Burgess]

Hey Dave what it sounds like to me is you are creating a direct short w/ no resistance. I am not sure what type of wire you are using but it needs resistanse to get hot. Think of it like a light bulb. They use Tungstun filament. It has a very high resistance which controls the Amperage. If you are using a wire with Low Resistance (copper, Aluminum, etc) there is little to no resitance there for you exceed the allowed Amperage of the PS.

Volts / Ohms (resistance) = Amps
Amps x Volts = Watts

Also you need to take into consideration the wattage of your PS. New ones go very high but you may be limited to a 100 or 200 watt PS.

[David DeCristoforo]

First of all, I want to thank everyone for taking the time to advise and suggest both here and on my other thread. I am throwing in the towel on this one. I am very adept at making things but this electronic stuff is just not my cup of tea. Time is of the essence for me and I've already spent more than I should have on this. So today, I'm popping over to my local Woodcraft store and picking up a "basic" power unit. I only need something to make my signature logo and what they have will do nicely. I already have everything else I need so I should be up and running by tonight. Thank you so much again for all the help!

DD

[Will Winder]

Like others have said, you probably need a load on the connection you are shorting.

You do this with a power resistor, you can get one for a couple bucks at radio shack.

[David DeCristoforo]

Just for the heck of it, I scrounged up a resistor. It's from Radio Shack and it's a 50 ohm 10 amp. Connected it to the pen tips and turned on the PS. This time it kept running. So... what does this mean? Do I need to stick a rizoid in somewhere? Or should a "proper" tip provide the correct load? Would a 3 inch length of nichrome wire provide the needed resistance? Or does the resistor need to go somewhere else? I'm willing to take one more shot at this before I quit on it. Remember... to me, looking at electrical schematics is like looking at a page written in Farsi!

[Tim Rinehart]

First of all, I want to thank everyone for taking the time to advise and suggest both here and on my other thread. I am throwing in the towel on this one. I am very adept at making things but this electronic stuff is just not my cup of tea. Time is of the essence for me and I've already spent more than I should have on this. So today, I'm popping over to my local Woodcraft store and picking up a "basic" power unit. I only need something to make my signature logo and what they have will do nicely. I already have everything else I need so I should be up and running by tonight. Thank you so much again for all the help!

DD
I completely go with you on that logic! Regardless of what your original intent for the one you get...the only thing I would want to make sure I have is some sort of rheostat on it for temperature/heat control. This will be something you'll end up playing with to get consistent results.
Let us know what you end up getting and of course the resulting "DD Branding" on a turning!!

[Jim Leslie]

In general P=EI .. in other words, watts = voltage X current. Formulas are here.
http://www.engineeringtoolbox.com/electrical-formulas-d_455.html
This table may help to give you an idea what kind of power (watts) you would need to heat nichrome.
http://www.heatersplus.com/nichrome.html
(http://www.heatersplus.com/nichrome.html)

[David DeCristoforo]

I really appreciate the input, Jim. The problem is, like I said, this stuff is incomprehensible to me! What I need is for someone to tell me exactly what I need to do to make this work. Like "Take a "X" ohm riziod and put it here." Or something like that. Otherwise, I'm dead. sorry to come across as dense but when it comes to this kind of stuff, I am! I have until around 1PM today to get this working or it's off to Woodcraft!!!

[David DeCristoforo]

OK... I put that resistor across the 5v pin and common. Then I hooked up the pen with the piece of the heater coil wire in it and it heated up orange/red hot! I might swap them and put the rizoid on the 12v pin and use the 5v for the pen. With a piece of "proper" nichrome wire I should be cooking?

[David DeCristoforo]

And... would this work to control the output?

http://www.amazon.com/Birddog-Distributing-Inc-Inline-Dimmer/dp/B004D5BVC4

[Jim Leslie]

I understand. I had to learn all this stuff to pass pass my amateur radio license exam. I do remember the mystery all too well, even though it was back in 1963!
At our woodturners meeting a couple of days ago, someone had one of these heavy-duty pyro blasters. It was made with a manual battery charger and dimmer switch.
And of course the homemade handle with a few inches of nichrome on the end.
So if you look at the table with the nichrome wire, 10.5 amps would get the 16 GA wire to 800 degrees F
10 amps, 12 volts
WATTS=VOLTS X AMPS
watts=12 X 10
120 watts
Now I don't know what temp is right and what temp the wire is red hot, but hope that gives a better idea.
Can't comment on the computer supply idea, but I do know that a standard manual battery charger does it.
The power requirement on mine on the label says 110V at 2A, so this makes it a 220 watt power supply - so to speak..
So a 60 watt transformer probably would not cut the mustard.
And I think the typical HD PC power supplies may be around 200+ watts. I'd use the car battery charger when I build mine.
Hope this helps..

[Rick Markham]

YAY!!!! See you needed a larger load, you were drawing too much amperage and it was assuming it was a short and throwing the breaker. I will let the experts chime in on permanently attaching the resistor, and whether the dimmer switch will work, but you've crossed the hurdle David, it sounds like you are in business to me :)

[David DeCristoforo]

"...you've crossed the hurdle..."

I thought so too but the thing got so hot it darn near melted everything. And since I have no way to regulate the output, the whole thing is pretty much useless. It's all in the trashcan now and I ordered a Burnmaster unit. If I got paid for the time and frustration I could have bought five of the things! I'm going now to look for all the hair I tore out of my head and see if I can put it back in while I wait for the unit to arrive.

So, thanx again to all for the assist.