Here in Italy incadescent bulbs are out of stock since 2012. Can I use an halogen one?
I've built my dbt with a 70 w bulb. I tested the trafo AS-4218 alone: primary connected to power inlet and secondaries disconnected and the bulb lights 🙁
Does it stay lit or just come on briefly ?
If it stays on your transformer doesn't look very healthy.
If it stays on your transformer doesn't look very healthy.
Just take that bulb money and buy a Variac.
If you are in this hobby, probably as good an investment as DMM.
We can not expect support on the build from a kit parts vendor, if the parts are good quality, which they certainly were from you.
Thats part of why we are here 🙂
Thats part of why we are here 🙂
Are you using a toroidal transformer ?
Have you mounted it correctly. It's possible that you have introduced a shorted turn if you have not mounted it correctly.
Have you mounted it correctly. It's possible that you have introduced a shorted turn if you have not mounted it correctly.
I used energy savers in mine, and it works most of the time, but sometimes the bulb comes on and something buzzes. We have been out of classic bulbs for years here.
A bulb+socket is as good an investment as a DMM, a variac doesn't replace a light bulb.
(me isolation transformer, plus variac, plus bulb)
That defeats the Mains Bulb Tester operation.
The filament is a PTC (positive temperature coefficient) resistor.
It warms up a lot on first start up and relies on near zero continuous current to allow it to cool down and thus let the equipment switch on.
If the equipment wiring is faulty such that excess continuous current would be drawn, then operation is different.
The filament warms up but the continued current draw warms the filament even more. The bulb lights up and absorbs most of the mains supply voltage. Typically a heavy load due to a mis-wire will only see 5% of the mains voltage at the mains transformer.
It is the automatic and very fast transition from warm filament to hot filament and the resulting 5% voltage at the input that prevents damage to faulty equipment.
Using a Variac to slowly get up to that 5% supply voltage will prevent the filament making it to the warm stage. The user has to notice something is wrong at that 5%. Most will not see the signs. The user will continue increasing the Variac on to 10% and to 15% and maybe higher until they hear, or see, the results of overheating. THAT IS TOO LATE. The damage has already started !!!!!!!!!!!
Yes.
They are still a PTC resistor.
They are still an incandescent bulb.
They are still made of Tungsten.
The slight difference is that the filament runs slightly hotter and thus the ratio of hot:cold resistance is a bit higher.
It is the hotter operation that emits a bit more light. A photoflood does similar, but has a life of just dozens of hours because it does not use the Halogen technology.
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update
Cazzo, I've cross connected the primaries!!!! Now the the bulb remains off. I've tried directly connecting (without dbt) and the secondaries have 16v circa. go on.
Cazzo, I've cross connected the primaries!!!! Now the the bulb remains off. I've tried directly connecting (without dbt) and the secondaries have 16v circa. go on.
Now I have connected ac power-toroid-rectifiers and my dmm say 17v. I think there is something wrong.
Checked the primaries putting the probes in parallel with the primary wires: 224v
Checked the primaries putting the probes in parallel with the primary wires: 224v
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acumos, do you have camera or smartphone that you can use to upload pictures? If you don't know how to do that we can help you learn.
thank you all for your help. So I connected the filter caps and measured the voltage putting the probes in "st_v-" and "st_v+" and is 48 V. Is it right? I think yes.
A X-Mas light string of Tungsten light bulbs may also work. There will alway be automotive [13.8 Vdc] Tungsten lightbulbs
I'm still puzzled as to what you did wrong in the first place ?
Did you connect the 110V primaries in parallel instead of in series ?
Even worse inverse parallel ?
Luckily transformers are pretty resilient when used with the correct fuse.
Did you connect the 110V primaries in parallel instead of in series ?
Even worse inverse parallel ?
Luckily transformers are pretty resilient when used with the correct fuse.