STL-24 Crystal Sync Controller for Bolex: An Improved Tobin TXM-24

Demonstration of the STL-24 crystal sync controller with a Bolex EL Mk3. The demonstrated form factor has a permanently attached cable that connects to the EBM/EL camera or ESM motor. However, I now make them with female panel connectors on top and bottom.
This project was a collaboration with Clive Tobin and Robert Ditto. Clive graciously shared some TXM-24 information to make the project easier. All three of us think it's important to keep the price reasonable and to get units into the hands of actual users (rather than resellers). I sell them for $300 like Clive did when he sold them directly.
Our twist on his TXM-24 design uses modern components, making it smaller and more reliable. Most of the Tobin TXM-24 PDF instructions still apply. It supports the 23.976, 24, and 25 fps in one package. Speed adjustment occurs with a flat-head screwdriver through a small hole to prevent you from changing it accidentally. The Alarm setting tries to sync near zero, which is impossible for Bolex electronics and triggers the Sync Alarm. The STL-24 uses a temperature compensated crystal oscillator (TCXO) that remains consistent between -30C (-22F) and 75C (158F). Its frequency stability is ~2.5ppm, eliminating the need for calibration. The STL-24 includes ESD protection to prevent damage to the sensitive electronics on its circuit board.
After posting this demo, I changed the form factor to have a female 7-pin Amphenol-Tuchel port on the top instead of a permanently attached cable. Customers from outside of the US requested this because it supports many cable options and simplifies repair if the cable gets damaged. The top port always connects to the Bolex camera or motor to keep sync (and typically draws power). An EBM requires power to be connected to the STL-24's bottom port. In this case, power passes through the STL-24 to the EBM. The ESM supports this approach too even though it has two 7-pin ports instead of one. When using an EL, I do not recommend connecting power to the STL-24's bottom port, as I haven't tested it.
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Contact me at [e-mail] if you'd like to order (through PayPal invoice) or have more questions. The price is $300 USD shipped in the continental US. If you need a cable, I can make one for additional cost. The cost varies depending on length and straight/right-angle connectors. As of Jan 2024, you're looking at $30-40 USD. The original 7P to 7P Bolex cables work if you have one.
For those who want to see more without contacting me yet, there are product announcement posts on Cinematography.com and the following Facebook groups: Bolex Camera Users (private) and What a Load of Bolex (public).

[@jmt9n]

Photos of the model without a permanently attached cable are available at cinematography.com/index.php?/forums/topic/96260-bolex-crystal-sync-controllers-for-el-esm-and-ebm-23976-24-and-25fps/

[@bolex]

Nice

[@Spectrumpicture]

You are awesome. No two ways about it.

[@TheCinematographyLab]

Great work!

[@ErnieCoco]

Can I ask the name of the tool you’re using to change the FPS on it?

[@jmt9n]

It's essentially a flat head screwdriver. I have a flat head tip in a Kobalt driver handle. I use the Kobalt electronic repair kit from Lowe's: www.lowes.com/pd/Kobalt-Electronic-repair-50-Piece-Steel-Hex-Shank-Screwdriver-Bit-Set/5001994777

[@geoffroydubreuilyoutube]

Hi Jason,
That's a very good piece of gear.
Are you making more?
If yes, where can we get it?
Thanks a lot!
Geo

[@jmt9n]

Hi Geo,
Please check the lengthy video description for technical details, price, and contact info.
Cheers,
Jason