Filament power supply

Hellerx44 · Dec 21, 2022

Hi
I have a question about switching power supply 5v 30 amps.
When I'm connecting it to tungsten filament wire 0.5 mm 3 cm long , after a time the power supply stops working. I think this is because of short protection. Are there any way to bypass this or you can advise me with another type of power supply.
Thanks in advance

danadak · Dec 21, 2022

Can you measure the current to confirm it exceeds power supply rating ?

One would be well advised to operate a supply within its ratings, for safety reasons
if for not other reason ....

Regards, Dana.

Hellerx44 · Dec 21, 2022

Thanks Dana for your reply
Actually it a ion source filement. The tungsten filament works on more current up to 50A.

Papabravo · Dec 21, 2022

Filament supplies were traditionally 6.3 VAC(rms) or 12.6 VAC(rms). I've never seen a DC filament supply, but I have seen stranger things.

Hellerx44 · Dec 21, 2022

[QUOTE="Papabravo, post: I've never seen a DC filament supply, but I have seen stranger things.
[/QUOTE]
Well. The ion source filement mostly Dc .but ac is available.
It easier to get high current with the dc rather than ac.

Lightium · Dec 21, 2022

The protection is there for a purpose.

JimB · Dec 21, 2022

Papabravo said:
Filament supplies were traditionally 6.3 VAC(rms) or 12.6 VAC(rms).

Hellerx44 said:
Actually it a ion source filement. The tungsten filament works on more current up to 50A.

I think that Heller is using something a bit bigger that a 12AU7

JimB

Dick Cappels · Dec 21, 2022

If you have a filament that needs a certain amount of current, you need to supply that amount of current to it. No way around it.

Papabravo · Dec 21, 2022

JimB said:
I think that Heller is using something a bit bigger that a 12AU7

JimB

True, but AC filament supplies don't require regulation either.

Hellerx44 · Dec 22, 2022

Dick Cappels said:
If you have a filament that needs a certain amount of current, you need to supply that amount of current to it. No way around it.

Done i found the solution to protect the power supply. I added 50amp diode. It works fine now.

Nigel Goodwin · Dec 22, 2022

Papabravo said:
Filament supplies were traditionally 6.3 VAC(rms) or 12.6 VAC(rms). I've never seen a DC filament supply, but I have seen stranger things.

There were numerous different voltages for valves, those two were just the most common 'modern' ones - and there's no reason or need for the supply to be AC, DC has advantages (less hum etc.), but it's easier and cheaper to feed them directly from a winding on the mains transformer.

As for the OP, it seems very likely he's simply using too small a supply to feed it - he even states it's a 30A supply, and the heater needs up to 50A.

Hellerx44 · Dec 22, 2022

Nigel Goodwin said:
As for the OP, it seems very likely he's simply using too small a supply to feed it - he even states it's a 30A supply, and the heater needs up to 50A.

I tried toroidal transformer it heats up like hell . Now i change it to 5v 40amps with 50amp diode.

Nigel Goodwin · Dec 22, 2022

Hellerx44 said:
I tried toroidal transformer it heats up like hell . Now i change it to 5v 40amps with 50amp diode.

What spec. was the toroid?. Does the device actually require DC?, or is AC OK as well?.

Hellerx44 · Dec 22, 2022

Im building particals accelerator. For the ion source filement ac or dc is ok. The toroidal transformer that i tried 40-0-40 300watt

Nigel Goodwin · Dec 22, 2022

Hellerx44 said:
Im building particals accelerator. For the ion source filement ac or dc is ok. The toroidal transformer that i tried 40-0-40 300watt

So how does that work as you need 5V?.

5V at 50A is (obviously) 250W - I would suggest getting a 5V toroid, rated at 500W (or preferably more).

The 300W toroid is (presumably) designed for an audio amplifier?, and not intended for continuous full power use.

And of course, transformers do get hot.

Lightium · Dec 22, 2022

Hellerx44 said:
Im building particals accelerator. For the ion source filement ac or dc is ok. The toroidal transformer that i tried 40-0-40 300watt

How many electrons do you expect to accelerate?

Hellerx44 · Dec 22, 2022

Lightium said:
How many electrons do you expect to accelerate?

Not electrons
Im trying to accelerat Protons

Nigel Goodwin · Dec 23, 2022

Hellerx44 said:
Not electrons
Im trying to accelerat Protons

My daughter used to go to ISIS (near Oxford, England) to run experiments using their particle accelerator (as part of her Phd), specifically using their neutron source - one of only three (I think?) in the world.

I once noticed she was on-line during the day, so Skyped her, and she was at ISIS working (you place your sample in the machine, press GO, and then wait) - so while we were Skyping she took het laptop for awalk, and showed me part of the facility. I can only describe it as a James Bond scene, it was just like you see in the movies.

On a different scale I feel

schmitt trigger · Dec 23, 2022

A 40-0-40 V, 300W toroid is only rated for 3.75 A. You require 50, small wonder it is overheating.

I join the chorus of everyone else who has advised you to use a correctly rated supply. There is no way around it.

Filament power supply

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