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

BrianShaw said:

Here’s an old source of non-engineering description. Page 39. Willard Morgan is a well-acknowledged expert in this area. Note, however, that this source is 1939 and pre-dates the “miniature” flash bulbs. Morgan writes of pyro paste in both foil- and wire-filled bulbs.

Like AgX, I’ve not noticed physical connection or pyro igniter in the “modern” miniature bulbs. But I also never interrogated the bulbs too much.

Morgan also writes of the need for ignition accuracy and precision when flash photography transitioned from open to synchronized flash.

https://www.worldcat.org/title/sync...ized-photography-with-flashbulbs/oclc/3297862

I have a first edition book and couldn’t easily find an online version. Maybe you can search more comprehensively than me if you are really interested.

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BrianShaw said:

I have same observations as you, Helge. While documentation describes early bulb design with pyro ignition, that technique, with the exception of magi-cubes, is not clearly evident in bulbs made during the 1960’s onward.

This isn’t relevant to that question (or the need for a capacitor in a tilt-a-mite) but I thought interesting:

https://www.pearl-hifi.com/06_Lit_A...ilips_Tech_Review/PTechReview-04-1939-148.pdf

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1. Batteries were relatively cheap and very easy to purchase almost anywhere
2. Battery circuits are incredibly simple and more servicable
   
3. Batteries can be used with solenoid synchronizers (important back in the days before hot shoes were commonplace)

1. A consistently large supply of current is available from the capacitor
2. The B-C system works best for multiple flash setups
3. Because the capacitor drains off small amounts of current, aging of the battery has little effect on the B-C system
4. The battery used in a B-C system can give a much longer life than those used in battery-only systems, often several years

Kth88 said:

I was recently looking for potential replacement capacitors for my Honeywell Tilt-A-Mite flash unit and stumbled across this fascinating thread. I’ve read through all of the comments that have been posted here over the past five years and feel that I might have something to contribute to help settle a number of unresolved questions that still linger.

I’m certainly not an expert or an authority on these questions; however, I’m an avid user of flashbulbs and have amassed a number of authoritative texts over the years that can help put many of these questions to rest. For reference, my primary texts are:

Flash Photography; Arnold, Rus; 1940

Flash for Better Photography; Bouie, Bill; 1956

Beginner’s Guide To Flash Photography; Harris, Percy; 1964​

I also have a variety of original flash manuals from the 1930s up to the 1960s for many of the flashbulb units that I own and use—some information comes from original camera manuals as well, which often include flash instructions for the flash units that accompany the cameras.

Question 1: Are there flashbulb units that do not use capacitors?
This question has more-or-less been answered here, but I can state pretty emphatically that there are DEFINITELY many flashbulb units that do not use capacitors. All flashbulb units from the late ‘30s to the late ‘40s did not include capacitors. “B-C” units were first introduced in the early ‘50s (“B-C” stands for “Battery-Capacitor”, or sometimes, rarely, “Battery-Condenser”). Many common flash units from the ‘50s were actually designed to function on either regular batteries or special B-C packs. The ubiquitous Kodak “Flasholder” series of flash units could accept either a pair of 1.5V C cells or a Kodak B-C pack that was the same size as two C cells but was comprised of a large capacitor and a space to hold a 22.5V battery. The popular Heiland Synchro-Mite used an almost identical system—this was the technological predecessor to the Honeywell Tilt-A-Mite, after Honeywell purchased the Heiland Corporation.

In the late ‘50s the Mallory battery company (which became Duracell) even sold special B-C “conversion units” that were the same size as common battery configurations, which could be used in any non-capacitor flash unit. These units allowed owners of flash units whose manufacturers did not offer a factory B-C option the ability to take advantage of a B-C power source.

Question 2: Why does the Tilt-A-Mite have a capacitor?
The main question that started this whole chain! Various different opinions have been offered in the past five years about the relationships between batteries, capacitors, voltages, currents, etc. To answer this question you have to understand the relationship between battery-only flash units and B-C flash units during the transition period of the mid-‘50s to the early ‘60s. That was the period during which the use of batteries only or B-C units was at its peak. There were advantages and disadvantages to each at that time.

Battery-only advantages:

1. Batteries were relatively cheap and very easy to purchase almost anywhere
2. Battery circuits are incredibly simple and more servicable
   
3. Batteries can be used with solenoid synchronizers (important back in the days before hot shoes were commonplace)

B-C advantages:

1. A consistently large supply of current is available from the capacitor
2. The B-C system works best for multiple flash setups
3. Because the capacitor drains off small amounts of current, aging of the battery has little effect on the B-C system
4. The battery used in a B-C system can give a much longer life than those used in battery-only systems, often several years

The big disadvantage of the B-C system during that period was that the initial cost of the B-C system was far higher than a battery-only system (also B-C systems could not be used with solenoid synchronizers).

It’s important to recognize that a flashbulb is ignited primarily by high current, not high voltage. A standard 1.5V battery could provide a high current for a short period of time (usually two batteries for 3V); on the other hand, an equivalent B-C unit used a high-voltage battery that would provide a low current to charge a capacitor, which then in turn would provide the high current during flash. So the voltages of the batteries are not as critical as it may seem: for instance, the Kodak Flasholder and Heiland Synchro-Mite guns each could use either two 1.5V C cells or a B-C unit charged by a 22.5V cell in the exact same equipment (fun fact: the 22.5V cells originally used in the ‘50s were known as “hearing aid” cells because they were developed for use in the rudimentary hearing aid systems of the time—high voltage and low current).

By the early ‘60s most mid-range to high-end flash units had gone to a built-in B-C system. There are many reasons for this: the costs of the B-C systems were coming down; photographers were beginning to use much longer rolls of film as 35mm film became much more popular, requiring more reliable firings of flashbulbs in quick succession; flash units in general were getting much smaller in response to consumer demands for smaller cameras, smaller flashbulbs, and more compact systems. Cheaper cameras continued to use battery-only flash up until the mid-‘60s, at which time cheap cameras had begun transitioning to flashcubes.

Question 3: Were there really “Photoflash” batteries back then? How were they different from other batteries?
Yes, I own examples of both photoflash and regular versions of batteries from that time period. This was the time before alkaline cells had hit the market. Photoflash batteries were identical in shape but used different chemistry than regular batteries at the time. The photoflash batteries were formulated for short bursts of high current, while regular batteries (commonly called “flashlight” batteries) were formulated to provide longer life of constant use at a lower current. Once the far-superior alkaline batteries became readily available in the late ‘60s and early ‘70s, the special “photoflash” batteries disappeared from the market. Incidentally, the older photoflash and regular batteries of the ‘50s are far lighter in weight than modern alkaline batteries of the same size. So when we think of putting two C cells in a flash unit and consider it to be somewhat heavy and clumsy, in the old days these would not have been as heavy as we would think them to be.
View attachment 271507

Question 4: What is the wiring diagram of a B-C flash unit?
There were two common types of B-C flash units in use at the time, one called the “open B-C system” and one called the “closed B-C system”. The open system was more popular and was set up like this:
View attachment 271509

In this system the insertion of a flashbulb into the unit would initiate the charging of the capacitor. The current through the flashbulb was kept low by the size of the resistor in the circuit.

The closed system was wired like this:
View attachment 271508

This system was less widely used because of the issues brought up in this forum: the battery would continuously charge the capacitor, and if the capacitor had any faults it would slowly discharge the battery over time.

I do not know which system the Tilt-A-Mite uses.

Question 5: How does a flashbulb actually get fired?
The business parts of a flashbulb are the wire leads, a filament, primer, and the combustible material. The filament is designed to burn out almost instantly once a current is passed through the wire leads. The sudden high heat generated by the burning filament in turn ignites the primer on the wire leads, which kicks off the main flash process. The primer is typically zirconium paste which is coated on the wire leads. It ignites in one or two milliseconds after the current is applied to the filament, producing an intense heat and exploding particles of ignited paste in all directions inside the bulb. In Class F bulbs the primer provides ALL of the light for the flashbulb. In standard bulbs the primer touches off the burning of the main combustible material. The amount of primer and the size and quantity of combustible material are held to very close tolerances so that the time-light performance is consistent from bulb to bulb.
View attachment 271510

There's a whole other conversation to be had regarding synchronization of flashbulbs with various shutter types, which I find fascinating as well, but that would be a whole separate long discussion!

If you've made it this far...thanks for reading!

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AgX said:

The grade or speed of combustion is independant of the electrical current.

On the timing one indeed may argue, whether a too slow warming of the electric filament results in the combustion starting retarded.

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Ruben Bensimon said:

Hi AgX
in my post of August 6/2019, I posted the pictures of the test I made with a Yashica 124G using a Tilt-A-Mite flashgun with a 123 battery, no capacitor.
The speeds were up to 1/500s, and the pics all came out properly exposed.
So there was no problem of timing or retarded combustion using a 123 battery
Why does the Honeywell Tilt-a-mite flash have a capacitor?

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Kth88 said:

B-C advantages:

1. A consistently large supply of current is available from the capacitor

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Ruben Bensimon said:

Hi AgX
in my post of August 6/2019, I posted the pictures of the test I made with a Yashica 124G using a Tilt-A-Mite flashgun with a 123 battery, no capacitor.
The speeds were up to 1/500s, and the pics all came out properly exposed.
So there was no problem of timing or retarded combustion using a 123 battery
Why does the Honeywell Tilt-a-mite flash have a capacitor?

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rainbowstew said:

I heard it explained one time as follows: a flash bulb draws about 1 amp of current when fired. This is a tremendous amount of current to come from a small battery (such as the 15 volt #504 or others, and they are not designed for that much current drain). Doing that repeatedly will cause a battery to wear out rather quickly. So, the capacitor is put into the circuit in parallel with the battery, and the capacitor is charged up at a much lower current drain rate than it would be drained if it fired the flashbulb. When the flashbulb is fired, the current is drained from the capacitor instead of the battery, and as soon as it is fired, the battery charges the capacitor again at the lower current drain rate. When the capacitor is fully charged, which usually does not take very long, the current will stop flowing from the battery. The capacitor is not affected by the large current drain. It is going to just keep doing that over and over again as long as the photographer wants to keep shooting flashbulb photos. So by having the capacitor set up in this manner, the battery will last much longer, usually about as long as the shelf life of the battery. This applies to any flash gun that uses a battery-capacitor arrangement.

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