Do It Yourself LED Strobe Trigger, Question.

Good day!  I need an LED strobe trigger for a Subal ND500 housing.  The trigger, as far as I can tell from looking at the commercial photos , 
consists of a hot shoe plug, two coin batteries with holders, two pairs of wires and two 5 mm LED's.  The price is about $300, which strikes
me as a bit high, given that the cost of the parts appears to be $10 to $15.

Do you know the circuit details, or know of somebody who has built their own LED trigger?  If so, are the circuit and parts details available?  
Thank you!

1 hour ago, Kraken de Mabini said:

Do you know the circuit details

These are the other $290. We are paying the know how like in the old tale “$1 to turn the screw, and $9,999 to know which screw to turn.”

The circuit board looks very simple but cracking TTL protocols, implementing high speed sync capabilities and other technologies requires a lot of technical knowledge. I agree that they are very expensive though. I wish they also offered us a product consisting in only a simple manual led trigger costing less than a third of the price

To clarify my above question:
The Subal strobe LED trigger is a simple On-Off device with no visible micro-controller or electronics, it appears to be mainly an On/Off switch. Fantasea offers a similar LED trigger.   
My question is: Do these devices rely solely on super bright LED's or do they use some a circuit or device to enhance the LED flash intensity?

A reader on this forum had posted a DIY circuit here, some time ago (apologies, forgot whom to credit). However, that circuit would have to be adjusted to work with button cells. I haven't had the need for it so far, but this winter I'm planning to upgrade my setup, and will need a flash trigger, so I suppose I'll try to make one around Nov/Dec time-frame (for Sony full frame). If successful, I'll share the design details here.

Kind regards,

Ajay

Thank you, Ajay, the above circuit with an fat battery and transistor is a bit complicated and bulky.  I can flash an Inon Z330 strobe with only a 3 V coin battery and a 5 mm white or red LED, with the light pulse being conducted by a standard fiberoptic cable. A super bright 5 mm LED should work even more reliably; super bright LED's are inexpensive and readily available. 

Solid state electronics may not be necessary to control the electric pulse as the camera's built-in flash switches on the current from the 3V battery to the LED for a millisecond or less.

The problem is how to built a hot shoe plug with contacts, one or two coin batteries, and wires - it will take a bit of tinkering to design a plug that is tough reliable.      

Yes, I think you have identified the main points needed for the modified design. I think one can buy hot shoe plugs fairly easily/cheaply. the other thing, I expect, is to put in a capacitor that gets charged by the battery and discharges into the LED. This way, regardless of the flash signal duration, the fiber optics cable will get a fixed amount of light. Obviously this means that the setup will only work with strobe power adjusted manually, but I am ok with that if it's a backup. And if I can get the design right, I'll will use the same button cells that my housing/dive comp use, (so, 2450 cells) since I carry spares anyway. Will return to this thread around the end of Nov/early Dec if I can get it going.

Kind regards,

Ajay

Good ideas and diagrams! 

Some practical questions:

What kind and color of LED's should one use? Red?  On the web, several LEDs are labelled as being UltraBright, but are they really?  Which dealers sell the hot shoe plugs and really bright LED's?

The above diagram by Bill has two grounds: one thru the 5K resistor to the hot shoe, the other goes to a generic ground. In practice, to what should this ground wire be connected? Otherwise,  if grounded via the hot shoe, both resistors will be bypassed.  

Good fun project!

3 hours ago, Kraken de Mabini said:

Good ideas and diagrams! 

Some practical questions:

What kind and color of LED's should one use? Red?  On the web, several LEDs are labelled as being UltraBright, but are they really?  Which dealers sell the hot shoe plugs and really bright LED's?

The above diagram by Bill has two grounds: one thru the 5K resistor to the hot shoe, the other goes to a generic ground. In practice, to what should this ground wire be connected? Otherwise,  if grounded via the hot shoe, both resistors will be bypassed.  

Good fun project!

 

Red is generally recommended, something in the 20,000 mCd range with a narrow beam angle.  There are even brighter ones around such as this:  https://www.ledsales.com.au/index.php?main_page=product_info&cPath=148_152_154_157&products_id=1806

Exorbitantly priced at $1 each.  Regarding the circuit the bottom ground connects to the battery negative and power flows from the battery through the LED and back while the 5K resistor limits current drawn from the hot shoe so it only acts to trigger the circuit.

For the hot shoe you could use something like this if there is space:  https://www.bhphotovideo.com/c/product/109454-REG/Kaiser_201301_PC_to_Hot_Shoe.html

Most ribbon cable type hot-shoe connectors I found were quite expensive $70-100 for a $2 part.

From the above, one can begin to write a parts list:

Hot shoe plug, probably hand made, with central and side electric contacts

Ribbon cable (#22 or #24 wire thickness, 4 to 8 wires across, about 100 mm long) 

Coin battery holders and 3V coin batteries, two

Resistors, 5K and 120K, one each

Transistor IRF 540, one

Superbright red LED's, two

LED to housing bracket, to be designed for each type of housing.

Perforated circuit board, thin, as needed. 

Tools, plastic glue, etc. as needed.

Elias: We are in Indoesia right now, when we get back, I can send you a hotshoe adapter if you want.

Bill

Yes, please.  That would be super!  I too will be in Lembeh later this Oct till mid Nov, and we can establish contact then so we can coordinate. 
Many thanks!

Following this thread. And considering to make myself a trigger, does anybody know where can I buy the Hotshoe already done ? I can find the Subal and the Aquatica ones, but for the price of it I can buy a complete trigger.

Hi Atus:  Here is how to build the hot shoe plug, I hope it is what you were looking for.

View archived post in: DIY Hot Shoe Plug for an Underwater Housing’s Camera.

On 11/7/2022 at 3:11 PM, atus said:

Following this thread. And considering to make myself a trigger, does anybody know where can I buy the Hotshoe already done ? I can find the Subal and the Aquatica ones, but for the price of it I can buy a complete trigger.

I've made a bunch of these DIY strobe triggers.  The best bet is to cut the hot shoe adapter off of an old housing, but even then, it may not be low profile enough to fit in your housing (that happened to me in one case).  In a pinch, you can make a very simple adapter using nothing but electrical tape, a rectangular piece of plastic from an old credit card, and a couple of wires.

I'm using a diy trigger. I bought a cheap land based flash trigger, something like $4, and just took the connector.

IMG_0425.HEIC IMG_0426.HEIC

Reef Photo has a good summary of flash triggers (see below),  only problem is that each sells for several hundred dollars.  One should be able to make a manual trigger for under $10, problem is to get the LED to flash brightly enough to trigger the strobe.  Super bright red LED's are inexpensive and readily available. Has anybody built a circuit to flash the LED's, such as the circuit described in this post by Bvanant ?

For commercial flash triggers, here is a summary by Reef Photo:

"A flash trigger is a device that allows you to trigger an external strobe using its own source of light rather than utilizing a camera flash or an electrical signal.  Some flash triggers use traditional flash tubes, but many are now utilizing very energy efficient LEDs.  Flash triggers may also be fully manual or incorporate a TTL Converter circuit.  The flash trigger uses a small pulse of light to fire a compatible strobe in sync with the camera shutter.

Flash Triggers for underwater housings are currently being manufactured by Nauticam, Sea & Sea, Subal, and Underwater Technics, plus more in development.  Some of the flash triggers are enclosed in finished shells, others are bare circuit boards with exposed LEDs.  The form is largely irrelevant to performance– they all are designed for a similar goal: Improve a camera’s performance in an underwater housing while simplifying strobe triggering.

Note that sometimes these devices are called TTL Converters or Optical TTL Converters, and some of the devices provide only electrical conversion and not optical triggering.

EXAMPLES:

BENEFITS OF FLASH TRIGGERS:

• Light-weight
• Do not require an electrical bulkhead
• Allow the use of light-weight fiber optic cables
• Can trigger as rapidly as the camera can shoot – even incontinuous
• Some provide TTL conversion technology
• Prevent additional o-ring maintenance required by electrical sync cords
• Are very reliable
• Use less camera battery power than a pop-up flash

LIMITATIONS:

• Not every strobe is compatible with every flash trigger
• Older housings may not have a flash trigger solution
• They require batteries (though many will allow a set of batteries to last for years)

MAKING THE SWITCH

If you are still shooting electrical sync cords or the pop-up flash on your camera takes too long to recycle, or you are looking at upgrading to a newer camera, it may well be time to consider a flash trigger.  The cost is not much more than that of buying electrical bulkheads and sync cords and once you switch, you are not likely to ever go back.  So what type should you choose?

The first thing to check is what is available for your camera and housing.  The options are growing almost every month and the current options can be seen below.  If you shoot strobes manually, you may only need a manual flash trigger which are often more economical than those with TTL conversion circuitry.  Nauticam has started shipping certain camera housings with a manual flash trigger installed as standard equipment (NA-D5 & NA-D500  $5,610-) and manual flash triggers are available for many existing models of camera housings at very economical pricing.

Recently, flash triggers with TTL conversion capability have come on the market and provide an exceptional solution for those who enjoy the convenience of TTL, but want the light weight and better overall performance of a flash trigger.

Whichever type of flash trigger you choose, the experience will be a refreshing change from traditional technologies.  Whether enthusiast or pro, optically triggered strobes are becoming the standard.

On 12/8/2022 at 10:11 PM, Kraken de Mabini said:

Hi Atus:  Here is how to build the hot shoe plug, I hope it is what you were looking for.

View archived post in: DIY Hot Shoe Plug for an Underwater Housing’s Camera.

 

Thank you very much !!!, sorry for the late reply, I've been on a trip and didn't enter the forum. Really really helpfull the whole thread!!

On 12/8/2022 at 10:38 PM, rwb500 said:

I've made a bunch of these DIY strobe triggers.  The best bet is to cut the hot shoe adapter off of an old housing, but even then, it may not be low profile enough to fit in your housing (that happened to me in one case).  In a pinch, you can make a very simple adapter using nothing but electrical tape, a rectangular piece of plastic from an old credit card, and a couple of wires.

Thank you, this was my first intention, but I want to keep te electrical trigger of my two housings in use, just in case. Anyway, it doesn't look difficult to make it by myself, and after watching the Kraken de Mabini's one the one doubt is use the plastic plug or design and print one with a 3d printer

2 hours ago, atus said:

Thank you, this was my first intention, but I want to keep te electrical trigger of my two housings in use, just in case. Anyway, it doesn't look difficult to make it by myself, and after watching the Kraken de Mabini's one the one doubt is use the plastic plug or design and print one with a 3d printer

attached is my designspark mechanical file (free program) for my 3D printed hot shoe adapter.  You can see the back piece pushes into the hot shoe, and has holes to run wires through to contact the center firing contact and the edge (ground/negative) contacts.  The whole front of that is my design to hold a giant battery and the LED's mount above all of it.  You'll just want to trim the hot shoe off of the rest of it.

hot shoe v5.rsdoc