Etcher Transformer Suggestion?

The problem with that transformer it's only 12 volts. When you got thru the capacitor/diode you'll pick up a few volts (3 or so extra on DC), but the AC will stay the same 12 volts. Ideally, for etching you'd like to have around 15 to 18 vdc and similar for AC. Some folks have lucked out by finding model train transformer at a decent price. They have both AC and DC voltages available. Something like this one: https://www.ebay.com/itm/273321650137?

You're looking for at least 24 to 30 VA (or 40 watts or more). If I could pick one, it would be perhaps 100 VA and 100 watts or so.

Your 12 vac transformer will work, but it will be a good bit slower.
 
I have a DPDT switch connected to a 12v7ah battery that gets charged when I’m not using it for the etching. The other side of the switch is hooked to a 40VA 18vac transformer. I switch it to etch (DC), hold for about 15 sec., clean steel with soap, flip switch to mark (AC), and hold for about 10 seconds and it’s done.
 
I built one 6 or 8 years ago based on his plans and have been very happy with it.
And thanks to a post Ken H> made on another forum that I came across recently while looking to make a homemade carbidizer, this etcher and a 20 buck dermel engraver is all you need to make a carbidizer. Thanks Ken
 
I currently have every other component listed in Mr. Crawford's tutorial... I ran into a snag with the transformer.

I ordered a Jameco 24 VAC 2 Amp with a power rating of 48VA... It was their pre-wired model. Problem is that the product description was incorrect and the unit I got was not center-tapped. Really strange too... since the box shows a picture of a center-tapped unit. So I have it sent back for a return.

It may be risky to go with the same company... but what do yall think about this guy? Seems like a winner. (24VAC, 2amps, CT, 48va power) And pretty cheap.

https://www.amazon.com/Jameco-Value...D=51y2YzEyHjL&preST=_SX342_QL70_&dpSrc=detail

 
Jimmy, the 24 vac transformer is a tad on the high voltage side. It will "work", but you'd have to be VERY careful about overheating your stencil. It really depends on the way the circuit that is used - full wave? Half wave? Smoothing capacitor used?

BTW, does a schematic show up anywhere on the link in your first post? I looked at the link and didn't find the schematic so don't really know what he's doing.
 
Last edited:
I have a 24VAC transformer on mine, which is based off of the Crawford plans. (Actually, I think I mainly referenced these plans, which are based off of Crawford's: http://www.logiudicecustomknives.com/knifeshop/etcher/index.shtml), and when I was using a mild steel etch pad, the 12V seemed very under powered, so I mostly used 24V, around 1 or 2 seconds on, 1 or 2 seconds off), but when I switched to a carbon etch pad, made from a motor brush, I noticed that the performance of the 12V setting improved considerably, so I rarely use 24V anymore.

Now, I should mention that on mine, I included a DPDT switch to add or remove the center tap to give me 12 OR 24 volts.
 
Ken H> said:
Jimmy, the 24 vac transformer is a tad on the high voltage side. It will "work", but you'd have to be VERY careful about overheating your stencil. It really depends on the way the circuit that is used - full wave? Half wave? Smoothing capacitor used?

BTW, does a schematic show up anywhere on the link in your first post? I looked at the link and didn't find the schematic so don't really know what he's doing.
Click to expand...

Hey Ken,

Here is the schematic I'm working off of.

 
OK, with that schematic that doesn't use a filtering capacitor, I'd go with the 24 volt setup - especially for the DC portion. By using the full wave bridge shown you'll only have 18 to 20 vdc (much ripple) to the pad. I like Count's idea of the DPDT switch to choose between 12 'n 24 volts.

This process isn't very critical to voltages, low volts just takes a tad longer than higher voltages do.
 
Does the amperage matter much for this application? Is 3A too high? Wouldn't this higher current just allow for faster etch times?

Thanks,
JK

Edit: The question above is still interesting to me, however, I realized that the amps on the transformer I'm planning to order is just 2A, which is in line with the Crawford guide lines. Thanks again.
 
I've checked the current draw used by my etcher and it varies during the stage of etch, and the design of stencil (how much open to be etched) AND the voltage. Higher voltage will draw more current which will generate more heat during etch. That is one reason to lift the etch pad every few seconds during etch, depending on amount of heat. Also, lifting the pad allows the gas generated during etch to be released.

If I remember correctly, I never saw more than 1 amp draw, so I think your 2 am transformer should be just fine. Wouldn't matter if it was a 10 amp transformer, it will still draw only the amount required by voltage and stencil.

Ken H>
 
Ken H> said:
I've checked the current draw used by my etcher and it varies during the stage of etch, and the design of stencil (how much open to be etched) AND the voltage. Higher voltage will draw more current which will generate more heat during etch. That is one reason to lift the etch pad every few seconds during etch, depending on amount of heat. Also, lifting the pad allows the gas generated during etch to be released.

If I remember correctly, I never saw more than 1 amp draw, so I think your 2 am transformer should be just fine. Wouldn't matter if it was a 10 amp transformer, it will still draw only the amount required by voltage and stencil.

Ken H>
Click to expand...

You're the man. Thanks Ken! I'll order the 24vac transformer posted above and see how it turns out! Sounds like it'll get the job done.
 
I shared this schematic a ton of times to fellow spanish talking knifemakers, electronic symbols are universal, just replace the 220v input with 110v and everything else is the same, I used old dichroic transformers (12v the heavy ones) you can find one of these in any old bipin or dichroic lamp

Pablo

ot8Lc64.jpg
 
PEU, that's as simple and good a schematic I've seen for an etcher. I especially like the 100uF capacitor across the DC which serves to smooth the ripple, and will increase the voltage of the DC output from 12vdc to around 15 or 16 voltage which is nice for etching.

BTW, PEU I looked for you at Blade this year but never saw you, I think you said you'd be walking around. My loss.

Ken H>
 
I think I ran into a snag. On AC I'm getting a very dark nice etch. On DC I'm getting pretty much nothing. It's "etching" but after 18 passes or so I can wipe it off with some water.

I utilized the step by step wire up on Crawford's site. I'm noticing that the diagram I posted on post #8 of this thread seems to differ some from crawford's description. He has the "3rd post" on the center tapped side utilized while the diagram has it taped off. Yall think this could be part of my issue?

Here's another question - Does the orientation of the rectifier matter? Is there a set numbering of the corners?



Crawford's step by step: http://chriscrawfordknives.com/tutorials/written-tutorials/electro-etcher/page-3/

Conflicting diagram:
 
You must log in or register to reply here.
Back
Top