Converting Graflex 3 cell flash into electronic bare bulb flash

Why screw up one of the few flashes that hasn't been appropriated by the Star Wars goons. Sunpak makes a decent flash with bare bulb.

Gosh... first film is dead and now flashbulbs are dead. What next???

Quote:

---

Originally Posted by BrianShaw

Gosh... first film is dead and now flashbulbs are dead. What next???

---

Old photographers.

I dream of being offered the opportunity to become a ghost to digital photogs.

Don't go hacking up a small on-camera strobe!!!!

A/ They squeeze a lot of circuitry inside on flexible circuit boards that are nearly impossible to close these units back together correctly again...

B/ The main cap inside is usually uninsulated and usually grounded to the cap case, (and hard to discharge, because it's hard to access the terminals) so you WILL get zapped as you mess around inside... (Even after you thought you discharged it well!!!)

C/ The usually thin, slender, linear flashtube (in most small flashes) is the wrong shape and difficult to get in the right position to focus the light correctly in a standard bulb reflector... (You might come somewhat close using at least a 200w/s flash with a glass enveloped (removable) flash tube...) These tubes are for the carefully designed/engineered reflectors in your flash...

D/ We have gotten spoiled using features like automatic flash output on our on camera strobes, and this will probably be disabled after conversion... So back to changing the f-stop as you change camera to subject distance... (Just like the old daze!!!!)

E/ After all the above, a med/large on-camera (hot shoe mounted) electronic flash does not have nearly the output of a medium sized flashbulb, so using it at the smaller stops you normally shoot at with LF flash, you might need f16, but barely might get f5.6 or f8 out of it... (Again, at least 200w/s would get closer to what you hoped for...)

Better to mount a side mounted (handle) auto flash on it, or something like a Norman 200 or 400B (manual)...

For now, as a test, put a camera bracket/handle with a mounting shoe on your camera, and try out your largest on-camera flash unit with it, and see if you are getting a close to useable light output with it...

Those old flashbulbs put out a whole lotta light!!!!

Steve K

OP perhaps check this thread.

http://www.largeformatphotography.in...=1#post1264035

Quick update.

The project is going ahead but I've made some changes to how I was originally going about it. I've decided not to mess with the internals of the vintage flash, simply because its very difficult to fit the components (square PCB in a round housing) and it would bee extremely unsafe (an aluminium tube with a large capacitor, being held barehanded etc).

So, what I'm doing is making a holder for the bare bulb (and the trigger circuit) using an old flashbulb base and a 3d printed insert. The charge used to previously ignite the flashbulb will now trigger the flash. Out of that base, a short wire is going to lead to a `flash box', containing the necessary flash components (including the main capacitor and control circuits). I'm going to attach this box under the Graflex bed (I've found some springs used to mount (eating) plates on walls, which are great for allowing the unit to be attached to my LF/Film cameras). The battery is currently planned to attach to the flash box. The advantage of this is that I'm not going to damage the flash, it will be far safer and I have more room to fit in my circuitry.


At this moment, I'm still designing and working out the circuitry. I've set up a breadboard with some of the components and I'm still hashing out some of the details. Its going to take a long time to properly work everything out and I'm only doing this as a personal project. I imagine that things will change significantly as things go on (I've already changed a lot with my circuits). When I've got a bit further with what I'm doing, I'll post an update.

Fantastic! I can't wait to see what you'll come up with!

I hope you realize that whatever electronic flash you come up with, it will not replicate the quantity or quality of light the original flashbulbs put out. Not even close. It's like using a starter pistol to simulate a cannon.

Hello! I ran across your post and am wondering how your project went? I am looking to modify a Leica Ceyoo flash unit as a bare bulb flash and need some help with the electronics. Did you ever complete your schematics? Any help would be greatly appreciated! Thanks,

Heinz