Why does the Honeywell Tilt-a-mite flash have a capacitor?

[DWThomas]

It does not need to be 15V.

I suppose that's the case, but the problem is still finding a form factor that will fit the space. The ubiquitous 9-volt rectangular battery with the two snaps on one end might work electrically, and they are everywhere (at least here in the US) but they are about twice as big as would fit in a Tilt-a-Mite. Don't know if two 3.x volt lithium cells might fit end-to-end; also not sure if they would work, but that could be a direction to look.

 

[AgX]

Batteries were chosen under different aspects. These may be voltage (to counter contact resistance), capacity, dimensions resp. volume and availability.
A standard flash battery size in West-Germany was a tiny 6V battery.

A 12V battery can be installed in the space taken by a 15V one.

 

[wiltw]

Batteries were chosen under different aspects. These may be voltage (to counter contact resistance), capacity, dimensions resp. volume and availability.
A standard flash battery size in West-Germany was a tiny 6V battery.

A 12V battery can be installed in the space taken by a 15V one.

According to information that I founbd, the 15v battery was 34.9mm x 15.1mm x 15.9mm ...do you know of 12v that would fit in its place?

 

[AgX]

Type A23

 

[wiltw]

Type A23

A23 battery is 28.5 mm long and 10.3 mm in diameter, which does not fit reasonably in a space designed for
34.9mm x 15.1mm x 15.9mm battery

 

[RalphLambrecht]

I thought all flashes had capacitors.

So did I

 

[AgX]

A23 battery is 28.5 mm long and 10.3 mm in diameter, which does not fit reasonably in a space designed for
34.9mm x 15.1mm x 15.9mm battery

I have several samples of A23 batteries and they are smaller in diameter and lenght than the 15V ones.
You yourself confirmed that above...

I did not say that fits, in the meaning of direct fit, but I said that "it can be installed" in that space,
We have lenghty explanations above of how to make an off the shelf capacitator fit. Thus it was clear that the user already has to use some tinkering.

 

[Diana Arduinna]

Could anybody tell me the output voltage in the PC sync cord? Is it 15V even with the capacitor? If not, is it possible to get it lesser without compromising the bulb firing? I want to be sure that it is compatible with all radio wireless transmitters...

 

[DWThomas]

Could anybody tell me the output voltage in the PC sync cord? Is it 15V even with the capacitor? If not, is it possible to get it lesser without compromising the bulb firing? I want to be sure that it is compatible with all radio wireless transmitters...

The flash contacts will see the battery voltage. The capacitor charges up to the battery voltage through a small resistor. Some of the discussion earlier in this thread suggested using a lower voltage battery, but I've not seen anyone here indicating they tried a lower voltage battery successfully.

The old bulb flashes passed the firing current directly through the mechanical shutter contacts. This old engineering type wonders if the newer flash triggers can reliably handle the current, not just the open circuit voltage. Maybe someone here has tried it and will jump in.

A few years back I found a schematic online FWIW:

 

[Diana Arduinna]

Thank you very much DWThomas!

 

[AgX]

Welcome to Apug !

There must be a minimum current go through the incandescant wire of the bulb, to start the whole shebang. So there is the resistance of that wire plus the contact restancies (bulb, battery, maybe capacitor, pc connector, trigger switch).
Back then batteries were chosen with a safety factor in mind, but also in mind with what batteries are widely spread.
As far as I know in times of AG bulbs the resp. small, compact batteries were just designed for flashes. They got 6V.

With small bulbs as AGB's for most of us easily available for cheap (aside of Reunion...) one always may try and find out what battery reliably fires the bulb.

 

[Sirius Glass]

It is part of the timing circuit. It controls the shape of the flash.

 

[E. von Hoegh]

I thought all flashes had capacitors.

The "light saber" I have holds three D cells, no capacitor.
The above posts regarding compact flashes with small batteies are correct in that the capacitor provides a good strong wallop to light the flashbulb, even when the battery is weak - because there is time to charge the cap. even from a weak battery while the flashbulb is being exchanged.

 

[KN4SMF]

Back in the day flashes called for photoflash batteries instead of the normal carbon zinc batteries used in everything else. The reason was that the photoflash batteries were engineered to deliver the higher current, instant demand requirements of bulbs. And they were prone to leak very badly. But all necessary evils in fulfilling their purpose. To some extent the photoflash batteries were their own "capacitor". BC flashes could operate dependably on other battery types. I remember well how flash unit dependably hinged on having good batteries. I also remember being blind for a half hour after a 25B bulb went off when pointed at us kids.

 

[AgX]

Back in the day flashes called for photoflash batteries instead of the normal carbon zinc batteries used in everything else. The reason was that the photoflash batteries were engineered to deliver the higher current, instant demand requirements of bulbs.

-) I do not know of special photoflash versions of otherwise standard batterie types.
What are these?

-) The specially for photoflash introduced 6V model I know of was a carbon zink model to my understanding, though I got samples of different built.

 

[RalphLambrecht]

Probably receiving a replacement cap today and it occurred to me that my other flash guns, like one on a Hawkeye Brownie or on my Polaroid land simply has a battery to ignite the flashbulb.

Any idea why the tilt-a-mite has a cap? esp since it uses a 15 volt battery you'd think it wouldn't be needed.

Pic for reference

https://c2.staticflickr.com/6/5058/5424747977_47f718fee4_b.jpg

Maybe to try to eliminate as much delay as possible?

I thought sall flash guns had capacitators?

 

[AgX]

This thread is only about incandescant flashes.

The first, and later maybe the most basic ones, had none.
Basically it is not even necessary, but in the end such capacitor employs the battery capacity much better and also does so more reliable.

 

[Jim Jones]

Dave -- Here is the basic BC flash circuit as I recall it from long ago. The capacitor isn't charged until a flash bulb is inserted. The resistor limits the charging current to much less than required to trigger the flash, but quickly charges the capacitor. When the sync contacts close, the bulb is connected directly across the capacitor. The current briefly drawn by the sync contacts through the resistor is not enough to significantly deplete the battery. Excuse the crude drawing.

 

[Vaughn]

My boys found a old disposal camera at the beach -- one of them got a bit of a shock when they took it apart...must of still had a charged capacitor!

 

[DWThomas]

Here is the basic BC flash circuit as I recall it from long ago. The capacitor isn't charged until a flash bulb is inserted. The resistor limits the charging current to much less than required to trigger the flash, but quickly charges the capacitor. When the sync contacts close, the bulb is connected directly across the capacitor. The current briefly drawn by the sync contacts through the resistor is not enough to significantly deplete the battery. Excuse the crude drawing.

Hi Jim, yes, that gets it down to the bare essentials! The claimed Tilt-a-Mite schematic I posted came from some other online source and didn't originate with me, I've never dug that deeply into the internals of my Tilt-a-Mite (which probably hasn't fired a flashbulb in 40 years!)

I suppose leaving the capacitor connected to the battery via the resistor would indeed leak away some power thru the cap -- maybe they wanted to keep the capacitor formed -- or maybe they also sold the batteries(!) -- or maybe they were working around some other company's patent (stranger things have happened!) The interesting challenge might be specifying that little test lamp bulb!

 

[DWThomas]

It is part of the timing circuit. It controls the shape of the flash.

Nay! I would argue the shape of the flash is set by incredibly rapid oxidation of shredded magnesium -- we are talking flash bulbs here. Technology only a step or two beyond the trough full of flash powder!

 

[AgX]

Yes, the "shape of the flash", the output/time characteristic curve is only determined by the flash bulb or rather the oxidizing pprocess taking place. Such can be tweaked by some parameters, and that is why there are bulbs with quite different characteristics.

The role of the electrics is only to make that tiny resistor wire inside the bulb hot, from then on it's to the bulb itself....

 

[Ruben Bensimon]

Yes, the "shape of the flash", the output/time characteristic curve is only determined by the flash bulb or rather the oxidizing pprocess taking place. Such can be tweaked by some parameters, and that is why there are bulbs with quite different characteristics.

The role of the electrics is only to make that tiny resistor wire inside the bulb hot, from then on it's to the bulb itself....

Yes, the "shape of the flash", the output/time characteristic curve is only determined by the flash bulb or rather the oxidizing pprocess taking place. Such can be tweaked by some parameters, and that is why there are bulbs with quite different characteristics.

The role of the electrics is only to make that tiny resistor wire inside the bulb hot, from then on it's to the bulb itself....

 

[Arklatexian]

So with these flashes, as the battery gets weak the bulb firing becomes impossible sooner?
I know non-BC flashes existed.

In the case of the Polaroid flash, it is called a 'Polaroid BC flash model 281' -- for Bulb-Capacitor

So OP, are you thinking about a different Polaroi flash than the one I mention?

Back in the days when we sold such things, "BC" meant "battery-capacitor" and yes, the capacitor was there so the flash would continue to work, even with a weak battery.........Regards!

 

[Ruben Bensimon]

Hi everyone
my Tilt A Mite's capacitor and 15v battery are both dead, so I just tried an experiment yesterday
My little Kodak Brownies from the 1960's (Starmite with AG1 bulbs, Starflash with M2/M3 bulbs) only use 2 AA batteries (2x1.5v= 3 volt), and have no built-in capacitor. So I looked for a 3v battery with fitting dimensions, and found the common and readily available CR123 battery. It's about the same size as the Tilt A Mite's capacitor or battery, just a bit thicker, it fits snug into the capacitor's spot. Question was, is this gonna work at all speeds? To find out, I fired some bulbs with a Nikon FE camera, and here's the result: At speed 1000, bulb does not fire. same at speed 500. At speed 250 and slower, the bulb does fire. Now my question is: could the sync (the delay, when you depress the shutter button, between the firing of the flash and the actual opening of the shutter - for example about 20 ms for M3 bulbs, allowing the burning bulb to reach peak power before the picture is taken) be affected when using just the battery without a capacitor? This is not relevant when using Kodak Brownies that have a fixed speed of about 1/60s, but it might be when using a Nikon SLR or similar.
So before I try my Tilt A Mite/CR123 battery/No capacitor combo with film, I would appreciate if anyone has an answer.
Cheers