The LM399 has built-in heater control, right? The data sheet doesn't mention, is it static off/on control, or simply a series of transistors that operate linearly in response to temperature? (I know current can vary on them, so I assume the later. This isn't in reference to anything specific, just a curiosity I've always had with the 399.)
It has a pass transistor and heater control circuit which operate linearly. The power drawn by the heater circuit is inversely proportional to external temperature as expected and drops to zero at about 85C. At 25C, it draws about 300 milliwatts. Operating voltage is from 9 to 40 volts.
The heater and zener allow for roughly an improvement of 5 to 20 times over a precision bandgap reference.
The LM399 has built-in heater control, right? The data sheet doesn't mention, is it static off/on control, or simply a series of transistors that operate linearly in response to temperature? (I know current can vary on them, so I assume the later. This isn't in reference to anything specific, just a curiosity I've always had with the 399.)
It has a pass transistor and heater control circuit which operate linearly. The power drawn by the heater circuit is inversely proportional to external temperature as expected and drops to zero at about 85C. At 25C, it draws about 300 milliwatts. Operating voltage is from 9 to 40 volts.
The heater and zener allow for roughly an improvement of 5 to 20 times over a precision bandgap reference.
Cool, that's about what I thought. I figured it might be neat to stick a simple shunt resistor on the heater power input (or output) hooked to a comparator to activate the "Oven" lamp on the 2005A. (Replaced with an LED, obviously.)
It would help keep things original looking too.
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The LM399 has built-in heater control, right? The data sheet doesn't mention, is it static off/on control, or simply a series of transistors that operate linearly in response to temperature? (I know current can vary on them, so I assume the later. This isn't in reference to anything specific, just a curiosity I've always had with the 399.)
It has a pass transistor and heater control circuit which operate linearly. The power drawn by the heater circuit is inversely proportional to external temperature as expected and drops to zero at about 85C. At 25C, it draws about 300 milliwatts. Operating voltage is from 9 to 40 volts.
The heater and zener allow for roughly an improvement of 5 to 20 times over a precision bandgap reference.
Cool, that's about what I thought. I figured it might be neat to stick a simple shunt resistor on the heater power input (or output) hooked to a comparator to activate the "Oven" lamp on the 2005A. (Replaced with an LED, obviously.)
It would help keep things original looking too.
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Or you could use the LTZ1000, which has an internal heater but external heater control. But actually, I think that LM399 heats up so quickly that it doesn't make sense to even have an oven light. These parts don't have to heat up a giant mass since it's just a heater built into the substrate of the chip.
Paint looks good.
I was told to use lightweight grease for the bearings/moving parts. I ended up using some firearms lubricant that I had. It is sort of like a slightly runny grease.
BTW - how did you ship that nichrome wire? I am sort of surprised it isn't here yet.
It has a pass transistor and heater control circuit which operate linearly. The power drawn by the heater circuit is inversely proportional to external temperature as expected and drops to zero at about 85C. At 25C, it draws about 300 milliwatts. Operating voltage is from 9 to 40 volts.
Cool, that's about what I thought. I figured it might be neat to stick a simple shunt resistor on the heater power input (or output) hooked to a comparator to activate the "Oven" lamp on the 2005A. (Replaced with an LED, obviously.)
You know, one issue I'm having is finding useful data on some of these old parts, like the diodes on the 2005A oven board. Man, I'd kill for some old data books!
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Hmm, I've got a buddy who's a Virginia Tech alumni, maybe he can find out if they do. I highly doubt it though.
Hmm, I've got a buddy who's a Virginia Tech alumni, maybe he can find out if they do. I highly doubt it though.
I can look at Concordia here, they had 1960s stuff back when I looked for vintage Tek parts info.
You know, one issue I'm having is finding useful data on some of these old parts, like the diodes on the 2005A oven board. Man, I'd kill for some old data books!
You know, one issue I'm having is finding useful data on some of these old parts, like the diodes on the 2005A oven board. Man, I'd kill for some old data books!
In the case of the interesting parts, I suspect Power Designs was grading them anyway so the original specifications would be of limited use. I usually end up reverse engineering the circuit in detail to find out what the specifications needed to be.
If I wanted to work from the part number, I would start is one of the Derivation and Tabulation Associates "D.A.T.A" books.
A fellow on the Antique Radio forum said they did their own semiconductor matching in house. I have seen some Sprague electrolytics in these supplies labeled, "For Power Designs," but I'm not sure what would be so special about them. I know at least in the HV supplies, they made their own transformers rather than buy them from suppliers.
Hmm, I've got a buddy who's a Virginia Tech alumni, maybe he can find out if they do. I highly doubt it though.
I can look at Concordia here, they had 1960s stuff back when I looked for vintage Tek parts info.
Ha! A fellow Montrealer!