Speedlite EX "high-voltage" : how high?

[pierrot]

I'm considering building an external power supply for my Speedlites for an indoors studio-like use. I'm (pretty) good in electronics so it shouldn't be that difficult, but for one point I can't guess: what is the high-voltage supposed to be?

I can't find no technical data on the subject. Does anyone use the "Transistor-pack E"? And if yes, could he/she give me the answer (in reading in the booklet or on the pack itself, or even by measuring the DC voltage with a voltmeter)?

That would help a lot (I don't dare applying 500VDC if the limit is, say, 310VDC)... :mrgreen:

[Mark Kemp]

The voltage on the batteries (and so also external batteries) is not that high, but the discharge voltage across the neon flash tube from the capacitor bank inside definitely is. It probably (not definitely) won't kill you, but it will give you a very nasty surprise. As you don't seem to have this figured out I suggest that you are not good enough at electronics to mess with the inside of flashguns! Do not do this, leave it to the pro's.

[xrunner123]

No offense, but if you want to 'measure it with a voltmeter' you're definitely out of your league.

[pierrot]

Hrm, both of you guys may be a bit too self-confident. This high DC voltage delivered by the external unit is certainly in between 300 and 500VDC - which is perfectly in the range of a well equipped DIY afficionado - and is not lethal if cleverly handled (do you think such a PS would by marketed with a single small "telephone" cord to connect it to the flash unit if not?). I wouldn't say such for AC, though.
So please let people "who know" give an appropriate answer, if you don't mind. ;)

[pturton]

Pierrot,

Because the info that you seek was not readily available, I took an alternate route to recycle my flashes slightly faster. I used 5 sub-C NiMh batteries salvaged from a hand vaccuum to make a battery pack that has enough current and capacity to run all day on my 550EX. Some others use small 6VDC lead-acid cells to do the same thing.

I decided that since I did not have the circuit for the HV input into the 550EX, it was not worth the risk of destroying the unit by exposing it to the wrong voltage or current source - something you are well aware of.

Guess I'm getting lazy in my years - 30 years ago I built a ringlight for use on my bellows mounted lens. Last month I bought a ringlite.

Paul

[pierrot]

Guess I'm getting lazy in my years - 30 years ago I built a ringlight for use on my bellows mounted lens. Last month I bought a ringlite.
Hehe, guess what? For me, it was last week.
This apart, I could build up some heavy-duty batteries packs, you're right. My intention was just for the fun of it more than for effective savings. And also to know for sure - pure curiosity - which DC voltage they produce with these (extremely) expensive "E-packs" ;)

[Mark Kemp]

Hrm, both of you guys may be a bit too self-confident. This high DC voltage delivered by the external unit is certainly in between 300 and 500VDC - which is perfectly in the range of a well equipped DIY afficionado - and is not lethal if cleverly handled (do you think such a PS would by marketed with a single small "telephone" cord to connect it to the flash unit if not?). I wouldn't say such for AC, though.
So please let people "who know" give an appropriate answer, if you don't mind. ;)

Ok I know nothing - I will resign immediately from my job as an electronics design engineer, which I have been doing for 20 years, then and take up another proffesion.

300V to 500V is absolutely lethal, but what will save you is the limited stored energy in the system which should mean that you only feel the high voltage for a few milliseconds at most. Provided that your heart doesn't stop from sheer surprise you just get a very nasty jolt.

The size of the cord relates to the current carried. The connector pin dielectric strength is the area of concern for voltage not the cord size.

An external battery pack should just be a larger capacity version of the pack that is inside the flashgun. The batteries are low voltage, about 6v. The high voltage is generated internally on a capacitor bank and applied very briefly to the flash tube to generate the flash. An external battery pack has more Ampere hours capacity, but still the same voltage, unless you are thinking of something very exotic.

Anyway - its up to you. I am concerned for your safety and the possible damage you will do your flashgun, but feel free to experiment just be careful.

[pierrot]

I fully agree with you, due to the shortness of the eventual shoxk, it would be very unpleasant but far from lethal (did you ever get a sholt from a car ignition system?). No doubt about that, so there's no point here.
What I just want to know are the specs of this external "Transistor-pack E": the name itself let me suppose that there is some voltage amplification inside, being directly applied to the flash capacitors (hashing being made in the pack, not in the flash) in order to shorten the loading cycle. Because the benefits of this pack are not mentionned as being its lifetime but the shorter recycling delay. What do you think? ;)

[Tom W]

Ok I know nothing - I will resign immediately from my job as an electronics design engineer, which I have been doing for 20 years, then and take up another proffesion.

300V to 500V is absolutely lethal, but what will save you is the limited stored energy in the system which should mean that you only feel the high voltage for a few milliseconds at most. Provided that your heart doesn't stop from sheer surprise you just get a very nasty jolt.

Absolutely, and it bears repeating. 120 volts can kill you, AC or DC. 50 volts has the potential to do so. Probably less under unusual circumstances. It isn't the voltage, its the current.

I came quite close to being killed by 135 volts DC - the control voltage for the circuit breaker tripping scheme that I was testing in a power plant several years ago. I was fortunate to have my sweaty hands act as a shunt, thus preventing the full current from passing through my chest. As it was, I either got tossed back away from the equipment, or I tossed myself back away from it. I don't quite remember. At any rate, it felt as though a giant hand had grabbed my chest and squeezed it very tightly. Not pleasant.

But, that was in a totally different circumstance. What I had was a bank of batteries capable of sustaining a couple of hundred amps of current for several minutes - plenty of punch to do the job. We're dealing with here is a much smaller amount of energy stored in the capacitor of the flash. Still enough to sting you pretty good, though the lethality is considerably less.

The size of the cord relates to the current carried. The connector pin dielectric strength is the area of concern for voltage not the cord size.

An external battery pack should just be a larger capacity version of the pack that is inside the flashgun. The batteries are low voltage, about 6v. The high voltage is generated internally on a capacitor bank and applied very briefly to the flash tube to generate the flash. An external battery pack has more Ampere hours capacity, but still the same voltage, unless you are thinking of something very exotic.

Anyway - its up to you. I am concerned for your safety and the possible damage you will do your flashgun, but feel free to experiment just be careful.

I'm with you there - I'd prefer to just set up a higher-capacity 6-volt power supply to replace the 4-AA batteries. Canon might make an external high-capacity power pack that has its own capacitor in it, but I don't know if I'd experiment in making a duplicate.

[iwatkins]

Of course, if you are willing to risk the flash, you could look at over volting the flash, i.e. try supplying 7 volts or 8 or 9 :)

I've no idea if this works for the Canon flashes but certainly used to work for some of the old Metz units. They used an external 9 volt battery pack, but if you put 12v through them they would recharge in approx. half the time.

Cheers

Ian

[Mark Kemp]

I fully agree with you, due to the shortness of the eventual shoxk, it would be very unpleasant but far from lethal (did you ever get a sholt from a car ignition system?). No doubt about that, so there's no point here.
What I just want to know are the specs of this external "Transistor-pack E": the name itself let me suppose that there is some voltage amplification inside, being directly applied to the flash capacitors (hashing being made in the pack, not in the flash) in order to shorten the loading cycle. Because the benefits of this pack are not mentionned as being its lifetime but the shorter recycling delay. What do you think? ;)

OK, well if Canon have provided a point where you can supply additional high voltage to the capacitors I would assume that 'transistor pack E' consists of more batteries, more boost converters and more capacitors so that there is effectively a bigger bank of stored charge for the tube. If this is the case you will need to match the external and internal voltages very closely, which is not easy, or simply disconnect and replace the internal system entirely (rather like disconnecting speakers in a hi fi when you use headphones) or whatever Canon designed in their system.

Just the voltage is not enough information.

Unless you can get fairly detailed specs including :-

Voltage, voltage tolerance, input impedance, connector pin out, polarity, capacitor ESR, charge current and discharge current and details of any circuit used to match the internal and external voltages.

it will be quite tricky to make anything work.

The problem is that you have no easy way to experiment. There is a good chance that a mistake will damage the flashgun, so trial and error will be more risky than usual. I would not even attempt this unless I had all the data first.

I would certainly pass on this one as a home project because :-

The chances of wrecking your flashgun are high
Even a non lethal shock is not nice
and there is the risk of exploding a capacitor with too much voltage or reverse voltage and that can cause some nasty burns

It is up to you whether you want to take the risk, but please also take every precaution as well.

I would recommend that you try to think of a different project, perhaps an infra red trigger or a timer remote control - something safer for both you and your equipment.

[sjms]

the average regulated output voltage of a HVBP is 330vdc. i own a Digital Camera Battery and had the appropriate cables for both the 550ex and 580ex along with various other device/cable interfaces. the outputs were 330vdc and 320vdc respectively. if you short the output it will give you a real nasty surprise.

[pierrot]

Hehe, I wasn't that far with my 310vdc example. ;)

What brand/model do you use? Do you have more information about the pinout?

[robertwgross]

You guys are just wasting your time until you specify which Canon EX Speedlite you are talking about.

For example, the 550EX has an external battery pack port on the side. 420EX does not.

---Bob Gross---

[pierrot]

You're right Robert, I forgot to mention it: a 550EX! :shock: