Hello all,
I'm new here but have looked around first. I'm hoping for some help on a project I'm trying to create.
I want to create a heated element which I can then use a small fan (either PC or small radial, 12/24V) to blow the air around a chamber. I'll be using partly polycarbonate and partly aluminium, with the lower glass transition temp being ~120C.
I'm looking to be able to vary the temperature between 0 and 75C. I'm thinking I'll create a wound wire (kanthal) and either,
a) connect to mains and vary voltage;
For this, I've calculated that if I have the resistance of the wire pre-determined at 175 ohms, I could then vary 135-230V using a dimmer switch and multimeter, giving me power of between ~50-300W which is more than ample for my enclosure. With this, my maximum current would be ~1.3A.
b) connect via 24V DC PSU and vary resistance;
For this, I've calculated that (looking to stay below 10A), I could achieve between 50-240W by varying the resistance between 2.4-11.5 ohms. This would result in maximum current of 10A at 2.4 ohms, 240W.
I think I prefer option b, but would certainly appreciate opinions!
This is also where I'm having difficulty trying to think through how I'd create the circuit. I think I'd look to use a specific length of wire with a known resistance (say, 2 ohms) then use a potentiometer in series to vary between .4-9.5 ohms. However, this would also result in the voltage changing across the coil - subsequently changing it's power so I'm unsure how I'd get around this? I've also only found potentiometers that are in kohms.
Another option I've thought of is having 10 branches with resistors varying between .4-11.5 ohms connecting in series to a a known 2 ohm wire and then using a single pole, 10 position rotary switch to vary the path through them?
Whilst typing this, I'm thinking possibly option a is best with a steady resistance of the coil, rather than even if I use the last option, as the resistors would also create unwanted heat.
I appreciate your time and would gratefully receive any and all help on this!
Mark
I'm new here but have looked around first. I'm hoping for some help on a project I'm trying to create.
I want to create a heated element which I can then use a small fan (either PC or small radial, 12/24V) to blow the air around a chamber. I'll be using partly polycarbonate and partly aluminium, with the lower glass transition temp being ~120C.
I'm looking to be able to vary the temperature between 0 and 75C. I'm thinking I'll create a wound wire (kanthal) and either,
a) connect to mains and vary voltage;
For this, I've calculated that if I have the resistance of the wire pre-determined at 175 ohms, I could then vary 135-230V using a dimmer switch and multimeter, giving me power of between ~50-300W which is more than ample for my enclosure. With this, my maximum current would be ~1.3A.
b) connect via 24V DC PSU and vary resistance;
For this, I've calculated that (looking to stay below 10A), I could achieve between 50-240W by varying the resistance between 2.4-11.5 ohms. This would result in maximum current of 10A at 2.4 ohms, 240W.
I think I prefer option b, but would certainly appreciate opinions!
This is also where I'm having difficulty trying to think through how I'd create the circuit. I think I'd look to use a specific length of wire with a known resistance (say, 2 ohms) then use a potentiometer in series to vary between .4-9.5 ohms. However, this would also result in the voltage changing across the coil - subsequently changing it's power so I'm unsure how I'd get around this? I've also only found potentiometers that are in kohms.
Another option I've thought of is having 10 branches with resistors varying between .4-11.5 ohms connecting in series to a a known 2 ohm wire and then using a single pole, 10 position rotary switch to vary the path through them?
Whilst typing this, I'm thinking possibly option a is best with a steady resistance of the coil, rather than even if I use the last option, as the resistors would also create unwanted heat.
I appreciate your time and would gratefully receive any and all help on this!
Mark
