Where are you located? Maybe someone local to you can help.

You can actually use a 12v power supply in the short term as long as you use a resistor and dial it in to the right current. For short distance stuff that could work. 

You can build a 120vdc power supply using a simple "isolation" transformer..theyre often used in arcade games/coin op stuff and are basically 120v in and out, but the output it much safer (but still dangerous 120v). Then just connect a bridge rectifier for dc and add a high wattage resistor or rheostsat for adjusting current. These things were simple, not highly regulated, and low current.

Jeff

On Feb 5, 2024, at 7:51 PM, Jomar Quilatan <jomarquilatan@gmail.com> wrote:



Thanks everyone for your input so far!  Yes, I had a hunch it had to do with some parameter of the magnet - so it was high inductance.

Before I consider getting my hands on a bench power supply capable of 120VDC (my first go-to guess), are there any recommendations of potentially cheaper solutions?  I have reached out to Paul to see if any 152950s are still kicking around.

After that I assume it’s just a quick series connection between the power supply, the resistor and the machine’s connectors? Obviously prior to any relays and comm connectivity.

Regards,

Jomar

On Mon, Feb 5, 2024 at 2:28 PM Harold Hallikainen via GreenKeys <greenkeys@mailman.qth.net> wrote:

Welcome to heavy metal RTTY!

As others have pointed out, due to the high inductance of selector
magnets, a high voltage supply is needed (it is possible to capture the
"kickback voltage" from the selector magnet and use it on the next space
to mark transition, though is is more complex). I use a Teletype 152950
supply from RTTY electronics as shown at https://w6iwi.org/rtty/ .

On interfacing the high voltage loop to a microcontroller, I use an SSR as
shown in https://w6iwi.org/rtty/DspTU2/kicadA/DspTuShemA.pdf (see K1).

Good luck!

Harold
https://w6iwi.org/rtty


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