Hi all,
I'm playing with thermochromic inks and would like some help
Thermochromic inks change colour at different temperatures so what im doing is using a 9v battery to heat up some copper wire
which changes the thermochromic ink's state. Below are images of what im talking about:
My problem is I'm going through a lot of 9volt batteries and was wondering if anyone knew of a more efficient and safe way. I was thinking of using an AC to 12V DC transformer but think with out modification i could blow something up seeing as I'm effectively creating a short circuit and would then be overloading the transformer, right?!?!
if anyone has some helpful advice I'd be very greatful
It depends very much on the current. Do you have a sense for how many amps you need to cause color changes? It would make sense to get a current-limited bench power supply so that you do not indeed overload your transformer.
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Not really sure about how many amps as i dont have the tools to test it but it starts to change state at 27?. Some copper tape and a 1.5v battery seems to do the job fine and I quickly tried it on a transformer which had a 5v/2.5amp output but it wasn't very effective and it changed state too slowly, maybe something a little above 2.5amps would work? A current limited bench power supply seems like a good idea, but look expensive and a bit bulky for my project though hmm
If 2.5A is not enough then "a bit bulky" is going be a necessity no matter what. Batteries can supply large peak currents, but of course you will drain them quickly. If you want the batteries to last, then they will necessarily be bulky
Perhaps your best bet would be a switching power supply like for laptops, which can put out something like 18V at ~5A.
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I have a 3.5Amp (variable 9.5 to 20volts) laptop adaptor that I could test. Do you think it has potential to get really hot / catch fire? Could I do anything to the output wires to prevent it burning/ shorting out if needed? Maybe I should use diodes or something?
It seems like bench power supplies cost £60 - £80, does this sound about right to you? not cheap
I have a 3.5Amp (variable 9.5 to 20volts) laptop adaptor that I could test. Do you think it has potential to get really hot / catch fire?
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You could add a fuse in series if you want to limit the current. A resettable fuse (PTC) would be a good investment as you will likely "blow" it several times.
It seems like bench power supplies cost £60 - £80, does this sound about right to you? not cheap
Sounds right, and it is a decent price Tinkering, like many hobbies, does cost some money. Shop around, however, for other deals. You can get DIY power supply kits for lower, though they assume some level of existing experience for assembly.
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You need a model train transformer. That will allow you to change the voltage to get the power/temperature you want. They are also designed so little kids don't hurt them or themselves by putting a coin on the tracks or doing other foolish things little kids do. Go to a model shop and see if they have a used one cheap.
