So Flash Bulbs are BRIGHT?! Anyone still using them?

[DWThomas]

Oh no kidding? So I can try to see if it will fire with a less powerful battery as long as its ends touch the proper contact points and complete the circuit? In the technical data I've been reading it appears most bulbs will fire with as little as 3 volts.

Yes, as far as I am aware, most early flashguns were simply a battery and the bulb where the sync closed the circuit. The voltage required is not at all high, it's the current that can be an obstacle. I have a 1957 vintage Argus C-3 with a flashgun that holds two 'C' cells, and that's it. It's likely that 'AA' or 'AAA' cells, especially the old zinc-carbon might have trouble supplying the current. So the "BC" (battery capacitor) flashguns stored a charge in a capacitor to supply a surge of current to fire the bulb. That permitted a much smaller package to perhaps mount on the camera instead of L brackets and those monster "light sabers."

I wasn't aware of those A23 12-volt batteries mentioned upthread, that might indeed be a worthy candidate -- and apparently here in the US, CVS pharmacies carry them because they are used in some medical widgets.

Electrolytic capacitors have a fluid or gel inside that tends to dry out, plus the actual dielectric layer is essentially just the surface oxide on an aluminum foil. Over time, if the capacitor is not charged occasionally, the oxide layer can become electrically leaky and lose effectiveness. Sometimes (often done with electronic flash units) charging, firing and discharging the unit a few times can "re-form" the oxide layer and restore operation, but one cannot count on it. I bring this up because I have several small electronic flashes that are decades old and they won't even start (you can normally hear the internal oscillator "sing") to begin charging because the capacitors are so far gone they overload the charge circuit. Fun stuff!

 

[BAC1967]

Electrolytic capacitors have a fluid or gel inside that tends to dry out, plus the actual dielectric layer is essentially just the surface oxide on an aluminum foil. Over time, if the capacitor is not charged occasionally, the oxide layer can become electrically leaky and lose effectiveness. Sometimes (often done with electronic flash units) charging, firing and discharging the unit a few times can "re-form" the oxide layer and restore operation, but one cannot count on it. I bring this up because I have several small electronic flashes that are decades old and they won't even start (you can normally hear the internal oscillator "sing") to begin charging because the capacitors are so far gone they overload the charge circuit. Fun stuff!

I have heard that capacitors in vintage radios will go bad from lack of use due to the material drying out. I have an old console stereo from around 1962 that still works great but it's used all the time. I have seen the exact same equipment, same age, not work due to bad capacitors. I have always attributed that to lack of use.

Some of those odd old batteries can be found new online but they are very expensive. I assume someone is custom building them. I like the idea of using an A23 battery in my old flashes, I'll have to see if I can get one to fit.

 

[AgX]

Use will not stop or decelerate deterioration of electrolytic capacitators.

 

[DWThomas]

Use will not stop or decelerate deterioration of electrolytic capacitators.

Yes and no. Use will not likely prevent drying out or leakage, might even accelerate it, but the oxide layer appears to be preserved, sometimes even restored, by having electric potential across it versus laying around discharged. We had a discussion a few years back about this with regard to some folks charging up their flashes every few months, even if they are not in regular use. I have to admit to not being very obsessive about that in my own case. I have a Canon 199 flash that was my father's and probably not used in the last 10 or 15 years of his life which is now dead, but a 188A of mine which is older than that but has had limited, but occasional use along the way, still functions -- err -- it did the last time I tried it!

(Insert disclaimer about the hazard of basing conclusions on samples of one ....)

 

[AgX]

Off Topic:
Yes, but that advised regular "re-forming" of the layer was seemingly meant to keep the capacitator, and thus the flash, ready for immediate use.
I have no valid information that such reforming after several years of neglet would be less effective, though it might take longer. But there are various formulas on this, even contrary. But regular switching-on of an electronic flash would not harm anyway...

Total failure of power capacitators of electronic flashes is still the great exception among my flashes.

 

[Punker]

I have a couple A23 batteries on order. Should be arriving on Monday to test.

So last night I was using my Mamiya Six Automat and the Tilt A Mite at a party. For the most part it worked great— but I had at least 3 bulbs flash the moment I stuck them into the flashgun— or, if unplugged, the moment I touched the pc cord to the terminal on the camera. Now I’m sporting a nice little blister on my index finger.

I’m wondering, as I haven’t tested it yet, was it perhaps because the shutter was cocked those times? Is there an order of operations I should be following? I’m guessing the cocking of the shutter somehow primes the capacitor or something to prepare it to fire. I have no electrical background so I don’t know if that even makes sense.

 

[AgX]

No, typically with such bulb flashes the capacitator is charged via the bulb and a protective resistor. Thus keeping a bulb fitted would drain your battery, unless there is some main-switch. The capacitator is only decharged by the shutter, by a parallel line.

 

[DWThomas]

Interestingly, a search for a schematic of the Tilt-a-Mite led me to a Flickr discussion about modifications which shows a schematic. This particular diagram shows the capacitor connected to the battery via a 2K resistor all the time. It's the Internet, so somebody argues that is incorrect, but the poster shows macro shots of the connections that seem to say he's right. Assuming that applies, any capacitor leakage will deplete the battery over time (a word to the wise ... )

Another diagram in that thread for a Polaroid flash shows a circuit like AgX describes where the flash bulb completes the charging circuit.

Anyway, cocking the shutter should not normally do anything. In general, the bulb is fired by closing a contact between the two conductors of the sync cable when the shutter opens. With the "PC" connector, the shutter closes a contact from the center wire of the flash sync connector to the shell. As that shell is often connected to the frame of the camera, a cable defect, or getting the bulb cattywampous plugging it in, could perhaps complete a circuit external to the cable and fire the bulb. The last time since I actually used my Tilt-A-Mite is measured in decades, so I have no recent experience, but I think even my aging mind would remember "that time the bulb went off in my fingers" if it had happened, so I assume it never did.

You might try a different flash -- electronic perhaps -- and check to see if the shutter/camera end of things is working correctly.

 

[Punker]

Thanks all. I’m thinking it has something to do with the camera. The other night before using the flash the shutter was acting weird. It seemed to sort itself out the next day so I went ahead and used it. The only other time I’ve used flashbulbs was with a TLR (but different flashgun) and I had no issues with discharge upon bulb insertion. I think I’ll try the Tilt A Mite on that camera and see what happens. Unfortunately it’s all made me a bit gun shy.

 

[Punker]

Interestingly, a search for a schematic of the Tilt-a-Mite led me to a Flickr discussion about modifications which shows a schematic.

Actually the first sentence in that discussion makes me think some contacts on the mechanical camera are touching prematurely and completing the circuit. The first poster writes “Back in the day, things were a bit easier- cameras had mechanical contacts-literally two pieces of metal, that touched to fire the flash at the appropriate time.“

 

[bvy]

Do you have a voltmeter? You don't need to be an electronics wiz to use one and do some simple tests to see exactly what's triggering it.

 

[Punker]

We have one at work, yeah. Good idea. I’ll give it a try next week. I suppose sticking the leads into the socket and fiddling with the settings, cocking the shutter and all that.

 

[Punker]

UPDATE: The voltmeter never registered a wrongful discharge in all the ways I suspected I’d done it nor have I had a misfire since Sunday (day after the party). Weird. Even had a flashcube misfire but now nothing. All the bulbs were from the same lot so perhaps there were a few bad eggs in there.

Also, the cheap 12V 23A batteries work! Just had to make a holder out of aluminum foil so that it both makes contact with the negative terminal and centers the battery so the positive terminal makes constant contact. This worked with both my Tilt-A-Mite II and my Nikon BC-7.

Link to test video

 

[DWThomas]

Excellent news -- a good data point to keep filed away here -- thanks!

 

[skorpiius]

I still use M3 and M2 flashbulbs with my Polaroid packfilm camera.
I also acquired a Honeywell Tilt-a-Mite flash which uses those two plus AG-1 bulbs (and maybe others) which I intend to use with my Yashica LM