I am trying to put together a bubble etch tank for making PCBs...
I figure I can use my compressor and some sort of homebrew regulator to give me the bubbles.... But I need to be able to heat the liquid as well to
around 45 degrees C...
I could use a fish tank heater, but thats about £30... can anyone think of any cheaper cunning solutions for keeping the liquid warm?
Needs to be consistantly at 45-50C for a couple of hours...
how much liquid ar you heating?
I'm sure there must be a way of using a £5 kettle from Tesco, remove the element and use that, but not sure how they control their heat. Do they have thermostats? Or a set current? Must be a clever way of doing that.
Hi,
How about an emmersion heater from a hot water tank, these are thermostatically controlled. You might find one in a tank that has been removed.
Regards
Bob
About a litre..... Its only got to be big enough to hang a couple of boards in...
The cheap kettles I have seen simply apply lots of energy to the water until the boiling vapour blows the switch closed again...
Electric lightbulb underneath the tank (not in the fluid). (not one of those new modern ones, a proper wasteful 100W bulb)
Vary the distance to vary the heating. If you have it at one end then you should generate some gentle convention based flow that will unify the
temperature.
Not precise, but its the right price.
The melting point of parafin wax is about 55deg C, so there may be a trick you could use with that to stabilise the temperature in a controlled
fashion (rather than just moving the heat source). Probably too complicated though.
Matt
or you could have a play with a slow cooker, they are controlled by wattage i think.
i have a fish tank heater.....
What about one of those heated hostess trolleys that were big in the 80's. Ready made tank and heat source all-in-one 
What about:
£9.98 Immersion Heater with Thermostat from ToolStation
http://www.toolstation.com/shop/Heating/Central+Heating/Immersion+Heater+Resettable+Thermostat+11/d230/sd2708/p12829
quote:
Originally posted by matt_gsxr
you should generate some gentle convention based flow that will unify the temperature.
quote:
Originally posted by Bluemoon
quote:
Originally posted by matt_gsxr
Electric lightbulb underneath the tank (not in the fluid). (not one of those new modern ones, a proper wasteful 100W bulb)
Vary the distance to vary the heating. If you have it at one end then you should generate some gentle convention based flow that will unify the temperature.
Not precise, but its the right price.
Matt
That's a good idea, thing is you can't directly heat the liquid as it will etch you heating element, so a light bulb/spot lamp/halogen lamp would be idea.. That and a glass thermometer..
Moving the fluid about is also a good idea and this is simply don using hinge and a moving base plate with the etch tray on, with a small motor+gearbox and cam to move the lot up and down.. Less trouble than a bubblier, I'd not want you to be blinded by a compressed air + acid accident...
Dan
The 5 quid kettle could be used as the element is quite small. Use a thermostat from an immersion heater to control the temperature. The cam idea to agitate the liquid is also good and cheap. I reckon the whole lot could be done for 20 quid.
12v water heater which can be found on ebay for about 3 quid of quid + a thermal switch
Dissolve anhydrous ferric chloride in water - 100C for an hour or so!
I'd go with your initial idea of using a fish tank heater - these have no eposed metal parts, are housed in glass case with plastic bits so a
waterproof - I assume to be acid proof too. Plus is has built in temperatur controller.
The kettle element would be metal surely, but not for long if immersed in acid. You could use it indirectly by heating water then passing water
through tubes - glass/plastic? that are in the etch tank.
google : http://www.willcoxonline.com/Bubbleetch/main.html
You definitely not murdered someone and are trying to displose of the remains? 
quote:
Originally posted by 02GF74
You definitely not murdered someone and are trying to displose of the remains?
quote:
Originally posted by britishtrident
quote:
Originally posted by 02GF74
You definitely not murdered someone and are trying to displose of the remains?
Apparently Bio washing powder is the best for that takes 6 months but destroys all the DNA.
why does it need to be heated?
I have a few fish tank heaters none of them go up to 50 degrees lol
website i just read said:
"If you aren't using a bubble tank, you need to agitate frequently to ensure even etching. Warm the etchant by putting the etching tray
inside a larger tray filled with boiling water - you want the etchant to be at least 30-50ºC for sensible etch times."
You don't have to heat the Ferric Chloride, I've made dozens of PCBs with the etchant at room temperature, it just takes longer to
etch.
Ideally you want to have a tall tank so you can stand the PCB on it's edge. This allows the etched copper falls to the bottom of the tank rather
than covering the board and slowing down the etching even further. For a single side board you can use a shallow tank and arrange to hold the board
upside down, spaced off the bottom.
If the tank is heatproof (e.g. Pyrex) then a light bulb under the tank (allowing free air movement) controlled with a dimmer would be sufficient to
warm up the solution a bit, though you'd need to keep an eye temperature and turn it down if required.