Bolex Crystal Sync Controllers for EL, ESM, and EBM (23.976, 24, and 25fps)

Jason Thompson · December 1, 2022

This project was a collaboration with @Clive Tobin and @Robert Ditto. Clive graciously shared some 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. Price includes USPS Priority shipping in the continental US.

Our twist on his TXM-24 design uses modern components, making it smaller and even more reliable. Most of the Tobin TXM-24 PDF instructions still apply. It supports the 23.976, 24, and 25 framerates in one package. Speed adjustment occurs 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 video on YouTube, I created another form factor with a female 7-pin Amphenol-Tuchel port on the top instead of a permanently attached cable. Customers from the European Bolex community 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. The STL-24's top port connects to the EBM's single 7-pin port. 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. Do not connect power to the STL-24's bottom port when using an EL.

I am willing to make units with a permanently attached cable until I run out of enclosures. Regardless of form factor, the price is $300 USD shipped in the continental US. If you need a cable, I can make one. The cost varies depending on length and straight/right-angle connectors. As of late 2022, you're looking at $30-45 USD. The original Bolex cables work too.

Robin Phillips · December 2, 2022

Definitely interested. please let me know how to order one

Jason Thompson · December 2, 2022

40 minutes ago, Robin Phillips said:

Definitely interested. please let me know how to order one

PM me. Once I know what you want, I can send you a PayPal invoice.

Arash Tohidi · December 30, 2022

Any plans/possibilities for H16 Rx?

Jason Thompson · December 30, 2022

23 minutes ago, Arash Tohidi said:

Any plans/possibilities for H16 Rx?

The STL-24 is a crystal sync controller - not a motor. It controls the sync ability built into the Bolex EL, EBM, and ESM. A Bolex ESM motor will work on a RX4 or RX5 (or any RX modified to have a 1:1 shaft).

Arash Tohidi · December 30, 2022

Why not make a complete product instead depending on yet another rare, vintage, expensive accessory?

Jason Thompson · December 30, 2022

26 minutes ago, Arash Tohidi said:

Why not make a complete product instead depending on yet another rare, vintage, expensive accessory?

We made a complete product. It's a crystal sync controller. There are many people with ELs and EBMs looking for them. Right now, we don't have any interest in the mechanical design work necessary to produce a self-contained sync motor like the Tobin TXM-26 (for 8:1 shafts). My father and I did this for fun - not to make tons of money. He's retired, and I have full-time software engineering employment.

Edited December 30, 2022 by Jason Thompson

Jason Thompson · December 30, 2022

Du-all has ESM motors listed on their website for $595. The self-contained Tobin crystal motors (TXM-10, TXM-20, and TXM-26) sell for ~$1000 if you can even find one. They were originally $600 (in the 2000s?). Unless you want to use 8:1 shaft cameras, the ESM + STL-24 approach is certainly more available than the Tobin self-contained crystal motors, which are the true unicorns.

Edited December 30, 2022 by Jason Thompson

Aapo Lettinen · December 31, 2022

14 hours ago, Arash Tohidi said:

Why not make a complete product instead depending on yet another rare, vintage, expensive accessory?

making a completely new motor is very time consuming and expensive and there needs to be a larger preorder to cover the starting costs. I have burnt my wallet so badly in previous projects that I don't want to start projects with less than 8 to 10 preorders which are partially or fully pre paid. It is just about losing lots of money if not being able to sell the full batch beforehand. I think one could expect losses of from 5k to 10k usd in a project like this if the motors are not pre paid and large enough batch sold... it is very common that the potential customers will vanish when you have actually the motor finished and available and you are only able to sell one or two when originally thought people would buy 20. So custom made preordered pre paid product possible but I don't think (based on my experiences) that the business model of first making, then selling will ever work with crystal sync motors and only the pre-paid custom order model works with them at all.

As for the other question, I don't have possibility to design and finish any new crystal motors in 2023. I might have something released in 2024 but not for Bolex so I suggest either trying to find a existing Bolex crystal motor (very rare but hands down the cheapest option if you can find one) or if that not possible, then hoping that Jason has a possibility to make a new motor for you

Marek Vesely · December 31, 2022

Hey guys! I'm one of the Jason's customers from Europe and I've been using his crystal sync controller for my Super 16 Bolex EL since September! I've now shot over 4000ft of film in my 400ft magazines with his crystal sync and I just couldn't be happier with the product. I have the removable cable version of the sync box, custom made right-angle cable for the EL (also from Jason!) and I also made an acrylic side plate for my EL where I can just stick the box onto the camera with special 3M velcro tape. Really awesome setup! You can see it how it looks on this image:

I've never had a single out-of-sync situation with Jason's box after these 4000ft of film! Not a single speed warning. I also own the original Bolex sync box for the EL and I had so many issues (I thought for a moment that my camera is broken) with keeping the motor at 24/25fps. It often ran much faster after 30 seconds of filming with the original Bolex sync-box.

I shot this sort of a test-project / music video with my factory converted S16 EL and Jason's STL-24 crystal sync in September (all shot at 25fps because of practical lighting here in EU). This can give you an idea how well the crystal works. ? You can watch it in 4K right here:

So at 300USD I think this is absolutely necessary piece of gear for EBM and EL owners when you basically can't get the original Tobin one nowadays. You can 100% rely on these on professional projects and film sets. Jason did not tell me to write this but I just wanted to let you know that these new STL-24 crystal boxes are out there and working on film sets! ? + Jason is just awesome to communicate with and offers extremely fast world-wide shipping.

Happy New Year!!

Edited December 31, 2022 by Marek Vesely