Modifying the Fellows A75 A4 laminator for making PCBs. Toner transfer the posh way!

Now, if I am making one thing up, it is usually straightforward to make a easy single-sided PCB up shortly, and professionally by utilizing the toner-transfer technique of PCB manufacturing. I have been doing it for years, however the outcomes are all the time a bit hit-and-miss. Use google if you have not heard of it earlier than, there are a lot of guides on the internet (though no two the identical!) , and I do not intend to duplicate these right here.

I’ve tried many various kinds of switch paper through the years, from the right stuff, to plain outdated A4 paper, the perfect I discovered for years was a replica of the New Scientist journal! Sadly they modified to thicker, shiney paper a number of years in the past, which does not work effectively in any respect. The most effective on the time of writing appears to be “The Economist”, which is a disgrace, because it’s nowhere close to pretty much as good a learn as “New Scientist” earlier than it get’s recycled into PCB making supplies!!

… anyway …

The final board I did, I attempted an experiment, by borrowing Mrs Doz’ laminator from her workplace. I concept was to see if it will switch the toner from the paper to the board, while preserving a continuing and regular strain on it. Nicely, outcomes had been blended… it actually pushed the board via too quick for correct switch to happen. I ended up transferring the toner with the standard garments iron, after which passing the board via the laminator, which resulted in an improved board after a few goes. It did, nevertheless give me an concept … make the motor run slower….

So, moderately than incur the spouse’s wrath and modify her laminator, I picked up a Fellows A75 A4 laminator from Argos for £16….

Electronic Repairing
Electronic Repairing
I initially examined it will take the thickness of the board by passing a clean piece of PCB inventory via it… yep, works a deal with.
So, to disassembly… There are Four pozi screws beneath (nice, not even some torx or weird safety screws to trouble me!)
So (from left to proper) we have now a necessary mug of tea, the motor, drive rollers and heaters, and at last a PCB on the suitable….
Electronic Repairing
Electronic Repairing
A few issues to note concerning the PCB… 
There’s some kind of timer in there to close the unit down after it has been on for 30 minutes (simply in case you allow it operating). It is unlikely to trouble us a lot….
The low voltage electronics (the timer, and LED’s and so forth) are pushed from an influence provide shaped by a wattless capacitor dropper… so a phrase of warning… all of those voltages on this board will seem like referenced to the mains. This could current us with a shock hazard and an issue if we wish to interface to them…
On to the motor….
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It is one thing I used to consult with as a “Le Cruzet” motor. A synchronous motor with in-built gear field. As we are able to see from it is label, it rotates at Four RPM (4.eight RPM in case you stay on that humorous little bit of the planet that makes use of 60Hz mains). That is a little bit of a ache. I hoped for a small DC motor I may drive with some PWM to get the velocity good and controlled (though if I used to be constructing an affordable laminator, I would be utilizing precisely this motor too!) 
So, how can we management it is velocity?
Nicely, it is synchronous, so we’ll have to decrease the AC frequency driving it …. Ugh … do not fancy this concept a lot.. producing a number of tens of hertz at 240 V RMS shouldn’t be going to be an affordable repair….
What about section modulation? Daft concept. It could fluctuate the velocity, however will destroy the motor’s torque, and will not fluctuate the frequency. Might trigger overheating and failure within the motor’s windings due to the resultant disagreeable waveform.
What about PWM? Nope, DC solely ….. or is it????
How about actually, actually sluggish PWM? Actually actually sluggish…. 
I am speaking about switching the AC to the motor on for .5 second, off for a second, and so forth ……
It will inch the board ahead, cook dinner it for a bit, and inch it ahead once more ….
It is simply silly sufficient to work….
So what do I want? 
A 555 timer, a slack handful of passives, a transistor and a relay…
or an arduino (or related, operating a modifed blink sketch!),a transistor and a relay…?
I am going to go together with the latter, because it’ll be straightforward to regulate by fudging the software program, and many of the {hardware} is constructed for us.
Electronic Repairing   Enter the relay module, and the extraordinary Digistump Tiny85 module… simply the ticket, and sufficiently small I ought to be capable of squeeze them into the case.

I’ve used the usually closed relay contacts, so if I do wish to use the laminator with out the velocity management, it should work high quality with the velocity management switched off. The relay contacts are linked in sequence with the motor, and the relay management pin to P0 of the digistump.

Electronic Repairing
A design is laser printed onto a chunk of paper from “The Economist”, and a take a look at piece of board inventory is cleaned up (I do know they seem to be a totally different dimension, nevertheless it’s solely a take a look at)

Electronic Repairing

The paper is tightly folded around the board so it does not transfer, and stuffed into the mouth of the hungry laminator! The “printed” facet must be dealing with the underside curler, as that seems to be the curler that is heated.

I left the velocity controller off (so the unit was operating at regular velocity) while it reached temperature.

I ran a few assessments, making an attempt totally different speeds.

Electronic Repairing   and into the sink!

I lastly settled on Four seconds off time, and 0.5s on time…. which produced good, repeatable outcomes ….

Electronic Repairing
Electronic Repairing

and left us with the digistump code trying like this….

void setup() {
  pinMode(0, OUTPUT);
}

void loop() {
  digitalWrite(0, HIGH); //Flip the motor off
  delay(4000);
  digitalWrite(0, LOW); //Flip the motor on
  delay(500);
}

So the electronics is all boxed up, and pushed from a redundant cell phone charger…

Electronic Repairing

Just a few phrases of warning….

We’re placing paper in right here, which is being uncovered to excessive temperatures for extra time than it will be in regular use…. If it ought to jam, there is a threat it may smoulder and catch hearth, and wreck your day… DON’T USE IT UNATTENDED!

Electronic Repairing   It clearly states “As much as 80 Micron” on the field. We’re actually taking the P*$$ right here, as my boards are 1.6mm thick, plus the paper (folded) so do not anticipate it to final … however whereas it does …. get making!

… oh, and you should use the identical concept to print a “slik display”…

Electronic Repairing

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