The Amp Garage Light Bulb Current Limiter

[Colossal]

Very cool, Martin. Thanks, as always, for all you do for this community. I have learned and continue to learn a lot from you. You and everybody else sharing great ideas, layouts, schematics, and experiences are why our community is great and continues to stand the test of time. You are a true gentleman and a scholar (but I use gentleman somewhat loosely )

[ChopSauce]

You guys make me feel so cheap ...

I'll admit this is a deluxe model, but it was entertaining to build and a pleasure to use.

BTW, the 2x EL34 amp draws 720 mA at 120V (no limiter, no signal), 430 mA at 99.8V with both 60W bulbs on, and 290 mA at 77.8V with one. By comparison, a 100W 4x 6L6 D-clone amp draws 1260 mA at 120V, 550 mA at 83.1V with both bulbs on, 340 mA at 60.8V with one (glowing quite brightly operating on 59 VAC). I highly recommend the power meter, which can be had for $25 or less. It comes alive at around 42 VAC, so it's working fine for the 100W amp/60W bulb case.

We sure don't have the same needs ...

[martin manning]

Inspired by sluckey's Volt/Amp/Watt meter addition to a Variac, I've added one to my Bulb Limiter II, which is typically plugged into a Variac. This meter module has a bright color display, and is attached to the limiter box. Only a matter of minutes to install. The Kill-A-Watt device I have been using for this purpose works ok, but its monochrome display is hard to read, and flipping through the screens is annoying.

Switching the bulb limiter to bypass, the display shows the Variac output, but not all the way down to zero volts. The description of this unit on Amazon says it operates from 80-300V, but the one I received is a 40-300V model per package markings, and indeed it turns on at 40V. It might be possible to connect the meter power supply upstream of the limiter bulbs so it would come alive at a lower DUT voltage (per sluckey's mod), but it didn't want to come apart easily, and it seems to work well enough as it is.

[xtian]

This is awesome, Martin!

Can you show photos of the wiring inside, and show what you've used for the input and output AC plug/socket?

[xtian]

Here is a quick shopping list from Amazon:

DROK AC multimeter https://www.amazon.com/gp/product/B09998YBHW
Square plenum box https://www.amazon.com/gp/product/B003A2GWX4
Square work cover https://www.amazon.com/gp/product/B005JC6PLW
2 pack toggle switch/output https://www.amazon.com/gp/product/B07WS31L87
Socket-to-bulb adapters https://www.amazon.com/gp/product/B07LDMP1LX
Extension cord https://www.amazon.com/gp/product/B002HWMY9E

[martin manning]

Under the hood shot. The meter I bought is this one: https://www.amazon.com/DROK-Frequency-E ... 1XHKQ&th=1
The 120V electrical hardware can be bought at the local Home Depot or whatever.