I have created an electromagnet, about 25mm long around a 12.5mm soft iron core. It has 12 full turns of 32 SWG copper enamelled wire. It is powered by 48V DC - for extemely quick (think eye blinking) pulses controlled by an on off switch.

However, the coil is getting incendiary hot very quickly.

Would switching to 26 or 24 AWG wire help?

(For background, this has to mimic a 1960s piece of tech).

TIA

 

hi Annie,
Do you need to use a 48Vdc voltage source?
Using your dimensions and windings, the coil will cook.
E

 

Would switching to 26 or 24 AWG wire help?

Yes that, or more turns.
If you calculate the power dissipated by the resistance of the wire for the applied voltage, you will easily see why it's overheating.

 

hi Annie,
Do you need to use a 48Vdc voltage source?
Using your dimensions and windings, the coil will cook.
E

Hi Eric,

yes 48V dc is needed (I think!) - at least, that’s how they were powered back in the 60’s, apparently.

 

Yes that, or more turns.
If you calculate the power dissipated by the resistance of the wire for the applied voltage, you will easily see why it's overheating.

crikey, this is out of my league!

So, pardon my ignorance, (the dimensions are non-negotiable unfortunately) if I created 8-10 turns of 26 AWG - would that solve the issue do you think?
Sorry to be a dope!

 

Hi A,
If you have a variable power supply, I would suggest you start at say 12V and carry out a blink test, slowly increasing the voltage and determine the voltage required to actuate the solenoid driven device. We can then suggest ways of reducing the 48V, to suit.
E

 

Hi A,
If you have a variable power supply, I would suggest you start at say 12V and carry out a blink test, slowly increasing the voltage and determine the voltage required to actuate the solenoid driven device. We can then suggest ways of reducing the 48V, to suit.
E

thanks Eric.
I don’t have a variable supply but will look into getting one.
Thank you

 

What is the purpose of these? How are they being used?

 

crikey, this is out of my league!

Well, if you are working with electrical devices, you should at least learn the simple Ohm's and Watt's laws.

 

12 turns? That's not enough.
Try 200 or 500 turns.

 

What is the purpose of these? How are they being used?

They are to power a puppet lip sync mechanism - exactly as used in Gerry Anderson shows. The basic premise is you power the magnet for a split second, it attracts a steel plate, which pulls the bottom lip down via a pivot mechanism, power off and the attraction stops, allowing a spring to pull the lip back to closed position.

 

12 turns? That's not enough.
Try 200 or 500 turns.

The magnet would be too large. Needs to fit inside a puppet head.

 

Well, if you are working with electrical devices, you should at least learn the simple Ohm's and Watt's laws.

Probably I should

 

Let’s do some math.

36ga copper wire is 1.36 Ohms per meter.

12 turns on a diameter of 12.5mm is 48 cm.

.48m x 1.36 is 0.65 Ohms

At 48V that is 74A and 3500W

That is more than twice the power of a typical space heater.

Likely, your power supply cannot provide that much power, which is why the coil did not nelt instantly.

 

Let’s do some math.

36ga copper wire is 1.36 Ohms per meter.

12 turns on a diameter of 12.5mm is 48 cm.

.48m x 1.36 is 0.65 Ohms

At 48V that is 74A and 3500W

That is more than twice the power of a typical space heater.

Likely, your power supply cannot provide that much power, which is why the coil did not nelt instantly.

So how would I solve this, given the dimensions I have? The coil itself cannot be larger diameter than 25mm - once wrapped around the 12.5mm core.

thanks

 

The magnet would be too large. Needs to fit inside a puppet head.

Use a smaller diameter iron rod. Put as many turns as space will allow.

 

So how would I solve this, given the dimensions I have? The coil itself cannot be larger diameter than 25mm - once wrapped around the 12.5mm core.

thanks

Buy a solenoid rated at 48 V.

 

the power disipated is volts times amps,
you have too much heat, so you need to,lower either the volts or the current.
your volts is fixed, so you need to increaee resistance,
if you use thinner wire, the resistance is increased , and you can get mire turns on, meaning longer wire, thus also increasing resistance.

note more turns increases mabnetisum, lower current loweres magnatisum,

 

The coil itself cannot be larger diameter than 25mm - once wrapped around the 12.5mm core.

Just read this. So you have 6.25mm for the coil. 36AWG wire is .127 mm, so you could get 49 layers of it, giving you 588 turns and needing only about 2% of the current you wound need with 12 turns.

3500/49 = 71W and 1.5A, which is a bit more reasonable.

 

Just read this. So you have 6.25mm for the coil. 36AWG wire is .127 mm, so you could get 49 layers of it, giving you 588 turns and needing only about 2% of the current you wound need with 12 turns.

3500/49 = 71W and 1.5A, which is a bit more reasonable.

The core is 12.5mm diameter?