built this for "Device Under Test" from the Tonnes

[Curranproducer]

OK- I want to help insure that all of my builds are safe from me goofing them up and frying iron. So I built this DUT power switch thingy form the Kevin O'Conner Tonnes of Tone book.[/img]

Here are the schematic and the wiring layout as well form the book.

so I built this thing, and it it working EXCEPT for the bulbs. should these only come on when the power is failing to get through the DUT? I am getting 120VAC in all the spots that I should, and i have put a couple of things on the power plugs but no bulb light. There is not a clear explanation in the book on what the light bulbs should do IF the unit you are hooking up is running just fine

[vibratoking]

You don't know how to use it, but at least you have one.

[martin manning]

See the TAG lightbulb limiter sticky thread. What you have there is just a fancy version of that. https://tubeamparchive.com/viewtopic.ph ... highlight=

[ToneMerc]

Seems like a real Rube Goldberg way of making it far more complex than it needs to be, not to mention costly.

TM

[John_P_WI]

The bulbs will only glow IF S2 is open (off) and there is load. Without anything connected to the device, the bulbs will not glow. The bulbs act as a large resistance and IF there is a large load such as a short will prevent damage (they would glow brightly in this situation). If the device is connected and the bulb(s) are very dim then S2 can be closed (on) allowing full line voltage to be applied to the device.

[Curranproducer]

well I was just building it to what Kevin has in his book, NOT trying to make anything harder than it needs to be! Believe me!!!! KISS is a motto I love! HAHAHAHAHAHAHA.

[Kagliostro]

OK apparatus test

http://www.youtube.com/watch?v=BhBhWi7c8us

Bad apparatus test

http://www.youtube.com/watch?v=68Zq1sDMbTM

I hope this can clarify the use to you

K

[Structo]

Excellent examples.

Although I don't recall the bulb getting brighter again.

I probably shut it down before that happens.

[martin manning]

There is no standby switch in a radio, so the re-glow in the video is likely the result of the tubes coming up in temperature and beginning to conduct some current.

In a guitar amp with a standby you see an initial bright glow as the reservoir charges at power on, then a dimming down to a steady glow reflecting just the filament current.

When the standby is switched on, you will see another momentary brightening as the remainder of the filters charge, followed by a glow that is somewhat brighter than it was with the standby off due to the additional current flowing through the tubes. Be aware that there can be some variation in this behavior depending upon how the standby is implemented. Remember also that with a bulb limiter in, voltages throughout the amp will be low, the cathodes of the tubes will not be at full operating temperature, and it will take more time for the filaments to heat up.

[Kagliostro]

Is a long time since I saw those video

if I'm not wrong the re-glowing is due to an increase in consumption of the circuit due to the selection of a transmitting station, this push the consumption of the AF part of the circuit, I'm sure also that this depends also on the kind of bulb you are using in reference with the whole circuit consumption

(a 50W lamp or a 100W lamp aren't the same thing)

K

[martin manning]

So I plugged a 50W amp into a bulb limiter with a 60W bulb and switched the main power and standby at the same time. Result: A bright glow which diminished to a dim glow after a few seconds, then after another 15 seconds or so an increase in brightness. Turning the standby off returned the bulb to a dim glow.

[Kagliostro]

A bright glow which diminished to a dim glow after a few seconds

the inrush current that charges filters cap

then after another 15 seconds or so an increase in brightness

tubes has reached theyr function point (heaters are heat)

Turning the standby off returned the bulb to a dim glow

the tubes aren't sucking current any more

---

I think that a 75W bulb will act a bit different

I suppose it to glow and dim at start then no more glow or only a very small amount

K

[martin manning]

I think that a 75W bulb will act a bit different.
I suppose it to glow and dim at start then no more glow or only a very small amount.

No, quite the opposite. I just tried it with a 75W. The initial dimming is more pronounced, and then the re-glow is much more noticable.

[Kagliostro]

Sorry

I wrote it backwards

K

[Structo]

Very interesting......