heating coil test run

hey,

now that i have the parts to make an extruder... i'd like to go ahead
and do that part now. i don't have the boards done... but i have
everything else. i'm wondering if there is an easy way to hook up the
wire to heat it and test. i dont want to fry anything, so is there
some sort of variable something or other i can use to make a crude
circuit to control the temperature?

would a dimmer switch be a crude possibility?

~Zach
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Dimmer switch doesn't work. I tried it for something else and I know. It's for a/c current only.

Running current through nichrome 80 when it isn't firmly attached to the extruder barrel is a rotten idea, too. That will cause the insulation to perish.


----- Original Message ----

From: Zach Hoeken

To: Reprap Developers

Sent: Monday, March 19, 2007 7:18:55 PM

Subject: heating coil test run



hey,



now that i have the parts to make an extruder... i'd like to go ahead

and do that part now. i don't have the boards done... but i have

everything else. i'm wondering if there is an easy way to hook up the

wire to heat it and test. i dont want to fry anything, so is there

some sort of variable something or other i can use to make a crude

circuit to control the temperature?



would a dimmer switch be a crude possibility?



~Zach

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Developers mailing list

Developers@reprap.org

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On Mon, 2007-03-19 at 22:18 -0400, Zach Hoeken wrote:
> now that i have the parts to make an extruder... i'd like to go ahead
> and do that part now. i don't have the boards done... but i have
> everything else. i'm wondering if there is an easy way to hook up the
> wire to heat it and test. i dont want to fry anything, so is there
> some sort of variable something or other i can use to make a crude
> circuit to control the temperature?
>
> would a dimmer switch be a crude possibility?

Use another length of naked nichrome wire. Stretch a metre out between 2
nails and make with some croc leads.

Vik :v)

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Quoting Zach Hoeken :

> now that i have the parts to make an extruder... i'd like to go ahead
> and do that part now. i don't have the boards done... but i have
> everything else. i'm wondering if there is an easy way to hook up the
> wire to heat it and test. i dont want to fry anything, so is there
> some sort of variable something or other i can use to make a crude
> circuit to control the temperature?
>
> would a dimmer switch be a crude possibility?

You have a fixed 12v old-PC power supply, right? Simplest thing would
probably be to connect it to the 5v output (check for shorts first...).
That's unlikely to fry anything.

Next level, you need a potentiometer and a heatsinked (any old lump of
metal) power transistor wired as an emitter follower - this will allow
you to vary the voltage. Assumning an NPN transistor, connect the
collector to +12, the base to the pot wiper, and the emitter to the
heater. The other end of the heater goes to ground. Connect the two
ends of the pot across the 12v supply. Turn the wiper to the pot's
ground end and switch on.

As you wind up the pot, the voltage on the emitter will track it (the
clue is in the name "emitter follower"...) allowing you to put any
power you like through your heater. You can use the same trick to make
a variable-speed motor (but add a reverse-biased diode across the motor
to short back EMF when the power goes off).

If you leave the heatsink off the transistor will get very very hot,
then resign permenantly from your service...

Best wishes

Adrian

Dr Adrian Bowyer
[staff.bath.ac.uk]
[reprap.org]
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would a tip 110 work for this?

On 3/20/07, Adrian Bowyer wrote:
> Quoting Zach Hoeken :
>
> > now that i have the parts to make an extruder... i'd like to go ahead
> > and do that part now. i don't have the boards done... but i have
> > everything else. i'm wondering if there is an easy way to hook up the
> > wire to heat it and test. i dont want to fry anything, so is there
> > some sort of variable something or other i can use to make a crude
> > circuit to control the temperature?
> >
> > would a dimmer switch be a crude possibility?
>
> You have a fixed 12v old-PC power supply, right? Simplest thing would
> probably be to connect it to the 5v output (check for shorts first...).
> That's unlikely to fry anything.
>
> Next level, you need a potentiometer and a heatsinked (any old lump of
> metal) power transistor wired as an emitter follower - this will allow
> you to vary the voltage. Assumning an NPN transistor, connect the
> collector to +12, the base to the pot wiper, and the emitter to the
> heater. The other end of the heater goes to ground. Connect the two
> ends of the pot across the 12v supply. Turn the wiper to the pot's
> ground end and switch on.
>
> As you wind up the pot, the voltage on the emitter will track it (the
> clue is in the name "emitter follower"...) allowing you to put any
> power you like through your heater. You can use the same trick to make
> a variable-speed motor (but add a reverse-biased diode across the motor
> to short back EMF when the power goes off).
>
> If you leave the heatsink off the transistor will get very very hot,
> then resign permenantly from your service...
>
> Best wishes
>
> Adrian
>
> Dr Adrian Bowyer
> [staff.bath.ac.uk]
> [reprap.org]
> _______________________________________________
> Developers mailing list
> Developers@reprap.org
> [reprap.org]
>
_______________________________________________
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Developers@reprap.org
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Quoting Zach Hoeken :

> would a tip 110 work for this?

Yup - it'd be perfect; darlingtons have very high current gain which
means they're practically designed for emitter followers. It'll only
get up to 11v out of 12v max, because of the voltage drop across the
transistor, but that shouldn't matter.

Best wishes

Adrian

Dr Adrian Bowyer
[staff.bath.ac.uk]
[reprap.org]

> On 3/20/07, Adrian Bowyer wrote:
>> Quoting Zach Hoeken :
>>
>> > now that i have the parts to make an extruder... i'd like to go ahead
>> > and do that part now. i don't have the boards done... but i have
>> > everything else. i'm wondering if there is an easy way to hook up the
>> > wire to heat it and test. i dont want to fry anything, so is there
>> > some sort of variable something or other i can use to make a crude
>> > circuit to control the temperature?
>> >
>> > would a dimmer switch be a crude possibility?
>>
>> You have a fixed 12v old-PC power supply, right? Simplest thing would
>> probably be to connect it to the 5v output (check for shorts first...).
>> That's unlikely to fry anything.
>>
>> Next level, you need a potentiometer and a heatsinked (any old lump of
>> metal) power transistor wired as an emitter follower - this will allow
>> you to vary the voltage. Assumning an NPN transistor, connect the
>> collector to +12, the base to the pot wiper, and the emitter to the
>> heater. The other end of the heater goes to ground. Connect the two
>> ends of the pot across the 12v supply. Turn the wiper to the pot's
>> ground end and switch on.
>>
>> As you wind up the pot, the voltage on the emitter will track it (the
>> clue is in the name "emitter follower"...) allowing you to put any
>> power you like through your heater. You can use the same trick to make
>> a variable-speed motor (but add a reverse-biased diode across the motor
>> to short back EMF when the power goes off).
>>
>> If you leave the heatsink off the transistor will get very very hot,
>> then resign permenantly from your service...
>>
>> Best wishes
>>
>> Adrian
>>
>> Dr Adrian Bowyer
>> [staff.bath.ac.uk]
>> [reprap.org]
>> _______________________________________________
>> Developers mailing list
>> Developers@reprap.org
>> [reprap.org]
>>
>



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nevermind, i googled it and found this page: [www.cpemma.co.uk]

that answered all my questions =)

On 3/20/07, Adrian Bowyer wrote:
> Quoting Zach Hoeken :
>
> > now that i have the parts to make an extruder... i'd like to go ahead
> > and do that part now. i don't have the boards done... but i have
> > everything else. i'm wondering if there is an easy way to hook up the
> > wire to heat it and test. i dont want to fry anything, so is there
> > some sort of variable something or other i can use to make a crude
> > circuit to control the temperature?
> >
> > would a dimmer switch be a crude possibility?
>
> You have a fixed 12v old-PC power supply, right? Simplest thing would
> probably be to connect it to the 5v output (check for shorts first...).
> That's unlikely to fry anything.
>
> Next level, you need a potentiometer and a heatsinked (any old lump of
> metal) power transistor wired as an emitter follower - this will allow
> you to vary the voltage. Assumning an NPN transistor, connect the
> collector to +12, the base to the pot wiper, and the emitter to the
> heater. The other end of the heater goes to ground. Connect the two
> ends of the pot across the 12v supply. Turn the wiper to the pot's
> ground end and switch on.
>
> As you wind up the pot, the voltage on the emitter will track it (the
> clue is in the name "emitter follower"...) allowing you to put any
> power you like through your heater. You can use the same trick to make
> a variable-speed motor (but add a reverse-biased diode across the motor
> to short back EMF when the power goes off).
>
> If you leave the heatsink off the transistor will get very very hot,
> then resign permenantly from your service...
>
> Best wishes
>
> Adrian
>
> Dr Adrian Bowyer
> [staff.bath.ac.uk]
> [reprap.org]
> _______________________________________________
> Developers mailing list
> Developers@reprap.org
> [reprap.org]
>
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