Morning! I am getting close (relatively speaking) to finishing up a TD125 with the SG4/MA-3D electronics that Pyramid developed. Since the SG4/MA-3D replaces the original electronics I am not using the original transformer.
I had a custom face plate made to keep the original strobe functional, but it's not lighting the way I have it wired at 120v. It looks like it the strobe actually runs on 220v.
Is it possible to run the strobe on 120v? With a different resistor than the stock one? Any insights on what that circuit would look like would be very appreciated.
Being extra cautious as I don't want to risk damaging the strobe.
I had a custom face plate made to keep the original strobe functional, but it's not lighting the way I have it wired at 120v. It looks like it the strobe actually runs on 220v.
Is it possible to run the strobe on 120v? With a different resistor than the stock one? Any insights on what that circuit would look like would be very appreciated.
Being extra cautious as I don't want to risk damaging the strobe.
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Unless Thorens found an odd high-voltage 'neon' (there are different gases) then the 47k on the plan is what I would expect to work on 120VAC. That they show it as 220V suggests it has a comes-with series resistor? 150k was sometimes included. Even so this would work on 120V, just not so bright.
Has it worked recently? Neons do go erratic and dead with age. The flickering pilot light on my old power strip hasn't flicked in a couple years. Strong light, or radioactives, or a careful(!) finger alongside, can enhance the starting.
IMHO, LEDs are better, and you can probably buy a complete kit. Maybe crystal controlled. Grid power frequency is good but can not be perfect.
Has it worked recently? Neons do go erratic and dead with age. The flickering pilot light on my old power strip hasn't flicked in a couple years. Strong light, or radioactives, or a careful(!) finger alongside, can enhance the starting.
IMHO, LEDs are better, and you can probably buy a complete kit. Maybe crystal controlled. Grid power frequency is good but can not be perfect.
The bulb works in another TD125 I have, so I know that's good. Is there any risk hooking the strobe directly to 120v mains, with the stock 47k in series?
Could be something simple like contacts need to be cleaned.
I did look into LEDs when i thought the bulb was out, definitely open to LEDs and something more accurate. I'll do some research on that too.
Could be something simple like contacts need to be cleaned.
I did look into LEDs when i thought the bulb was out, definitely open to LEDs and something more accurate. I'll do some research on that too.
TD-125 neon strobe lamps in my rather limited experience don't work on 120Vrms even with 33K resistor. I think the Pyramid controller should be more stable than the stock drive electronics. I have forgotten whether the SG-4 allows you to adjust the quadrature phase angle to compensate for variations in motor build geometry.
You can also use two LEDs wired in parallel but reversed directions. The right size series cap will limit the power without dissipating power itself. You get the correct number of pulses and the two LEDs protect each other from too much reverse voltage. I just don't remember the value of the cap, but it's not large. The deluxe version adds zeners so the LEDs only light on the very top of the waveform, giving a slightly sharper image of the strobe disk.
Please check, the 220 V was 50 Hz or 60 Hz.
Here we used to get turntables with the edge marked for 50 and 60 Hz, so that was not an issue.
You may be able to rig a circuit to fire LEDs, with a crystal oscillator in order to meet your need.
Search for 'LED timing light' also.
For a far out look, you could try a high output LED, similar to cell phone flash LED.
Here we used to get turntables with the edge marked for 50 and 60 Hz, so that was not an issue.
You may be able to rig a circuit to fire LEDs, with a crystal oscillator in order to meet your need.
Search for 'LED timing light' also.
For a far out look, you could try a high output LED, similar to cell phone flash LED.
Well shoot, I was hoping this was going to be simple. Thanks for the suggestions on working a system with LEDs, I found one circuit on vinyl engine:
https://www.vinylengine.com/diy-strobe.shtml
Unfortunately I need more of a step-by-step guide. @Conrad Hoffman do happen to have a link to that system? I might have seen what you are talking about.
https://www.vinylengine.com/diy-strobe.shtml
Unfortunately I need more of a step-by-step guide. @Conrad Hoffman do happen to have a link to that system? I might have seen what you are talking about.
The circuit I'm describing is extremely simple. I'll try to find mine tonight and see if I can see the values. IMO, line frequency accuracy in the USA is far better than everybody seems to think. There's little benefit in doing fancy crystal oscillators unless you just like doing the circuitry and being able to boast about the accuracy. I'm in that category but am too lazy to build one. 🙂
There were a number of DIY builds in this thread: https://www.diyaudio.com/community/threads/help-me-please-with-this-turntable-100hz-strobe.320593/
I'll check that one out, thanks @Pyramid . And since you're here- preview! Thanks for taking a look at the values @Conrad Hoffman , I'm with you for now I'd like to get something going, this project has been a long time coming.
OK, here's the "deluxe" version of the strobe, from which I've removed all the insulation so you can see it. First, this is directly line powered so needs to be absolutely completely insulated. It's best suited to go inside something like a turntable where nobody can get near it. 120 VAC line comes to the left side of the big cap, a 0.1 uF 1500 V film cap. From the right side of the cap we go through two 1N5253 500 mW zeners. They sharpen the flash. Any 25 volt 500 mW zener should do. Now through a pair of bright white LEDs wired opposite each other so they light on opposite polarities. This will give you the same flash frequency as a neon bulb. The forward voltage of each LED protects the other from exceeding it's reverse voltage, which is usually low. Back to neutral through a 220 ohm 1/4 W resistor. There's a 0.001 uF cap across the LEDs which, combined with the 220 ohms, kills potentially damaging line noise. Looking at the photo at this scale I see I never soldered one end of the little cap! It wouldn't be a mistake to run this through a small fuse, maybe 1/8 amp or so, though the resistor or zeners would act like a fuse if the big cap ever failed. Again, complete insulation should you decide to build one of these and you assume all responsibility for doing it safely. If you're not used to working with line voltage, this isn't something you should do.
Here the Chinese torches use 390K across a 455J / 400V to step down the line voltage, then bridge rectifier to battery.
So what you did is a normal thing.
Maybe for safety's sake, stick the cap to a bit of old PCB with hot melt, and use wires to the LED at the table edge.
The card can be fastened to the interior with a wood screw, or whatever is suitable...
Some new Thorens units use an external supply, so this means a new mains cord is needed.
So what you did is a normal thing.
Maybe for safety's sake, stick the cap to a bit of old PCB with hot melt, and use wires to the LED at the table edge.
The card can be fastened to the interior with a wood screw, or whatever is suitable...
Some new Thorens units use an external supply, so this means a new mains cord is needed.
Thanks so much @Conrad Hoffman !!! So helpful and I'll get parts for that. I'm going to head down to our local surplus store as they have a couple buckets of neon bulbs I can try, but long term I like this LED solution much better and will get parts on my next order.