Armortek

Perhaps this might be too broad a topic, but?
I have been trying to search for relevant items on the forum and coming up with a blank. So what I need to have is, guidance on connecting Muzzel Flash and MG Flash LEDs to Benedinni Sound Cards.
Plus a related topic of how to select and connect LEDs together so as to be compatible with the Power of the Sound Card and the 24v Supply of the Tanks.
I hope that, in fact I am sure that, others will be able to provide the links to the topics on the Forum that I cannot find with ease I have spent a lot of time on this to no avail
Many thanks
Steve

Steve, there is an option on the TBS5 for both MG fire and Main gun fire using LED if I remember right its universal output 6 the centre pin is 5v+ top and bottom pins are –negative one of the negatives operates the MG the other the main gun you don’t need resistors for the LED’s as they are built into the board, the MG can be split to operate both hull and turret MG both simultaneously.

An LED is a light emitting diode.

A diode is a semiconductor junction which allows the passage of current when its forward voltage is exceeded.

LEDs emit light, of varying frequencies and hence colour, depending on the material used for the diode junction.

The two important values needed when selecting an LED are:

1) the forward voltage Vf. This is the minimum voltage across the LED necessary to make the diode conduct and hence the LED to produce light.

2) the forward current If. This is the current which will pass when the diode is conducting, up to a maximum, at which point the magic smoke escapes and it stops working.

The Benedini TBS5 is run from a 5 volt supply and has a 270 ohm resistor in series with the main gun and MG outputs on connector 6.

Making the assumption that the LED has a fairly standard forward voltage of 2 volts, we can use Ohm's Law to calculate that the forward current will be the supply voltage less the forward voltage and all divided by the resistance. This works out to be:

( 5V - 2V ) / 270R, which equals 0.011A, or 11mA.

This is fine for a standard LED with a maximum forward current of 20mA or so.

However, to use higher powered LEDs, so that the main gun muzzle flash will be visible in daylight, much more current is needed, which is why I designed the original recoil unit around a high powered transistor switching chip, as the Benedini by itself cannot provide the current necessary to illuminate a high powered LED.

It should also be noted that it will only work when connected the right way round. The picture below shows the ways to identify the positive and negative pins on an LED.
As Mark stated, the centre pin on the TBS5 is the positive supply, so needs to be connected to the Anode on the LED. The top and bottom pins connect to the negative supply when activated by a sound, so need to be connected to the Cathode of the LED.

If you run two LEDs in parallel, the voltage drop will be the same, but each LED will only receive half of the 11mA, so will be dimmer and may not even light. Also, if the voltage drops across the two LEDs are slightly different, one will take a much higher proportion of the available current than the other, so the subordinate one may not light at all.

If you run them in series, the voltage drop across the pair doubles, so the available current becomes:

(5v -2v -2v) / 270R, which equals 0.0037A, or 3.7mA, which may just light the LEDs. But probably not.

Adrian.

Thank you Mark and Adrian for your replies, food for thought.
It seems that connecting MGs is relatively easy. I will use an Action Electronics Switch, which I have used on my Tiger and Mark IV for a variety of functions. The question is how to run a more powerful LED set up suitable for Muzzle Flash. Is there, or do you have Adrian, an independent switch/device that will allow say the Tanks 24v supply to run a cluster of LEDs? Or is the electronics simple enough for a safe build?
Steve

It's very easy to build a switch that connects with a battery (2x 1,5 volt in my case) and the benedini sound card.

I use it in my Panther

http://www.armortek.co.uk/Forum3b/viewt ... 875#p33137

Maarten, your U Tube Video is coming through as not available, so are you able to provide a circuit diagram so I can get the soldering Iron out and reproduce your Switch?
It seems that is the way to go!
Thanks Steve

Hello here is the diagram for the Muzzle flash in 5 volt, 12 volt or 24 volt. You can use it with 2 watt high density leds. One of my electronic wiz brothers designed it for me a year ago.



I've just made an example to give you an impression of the materials used






It works for me and my Benedini, but, as always, Soldering is at your own risk

Hi Maarten
I must confess I do not follow your circuit diagrams. For a beginner such as my self to understand, ought there not be wires returning to the Negative pole of the Battery and to the common pin of the Benedini board? if so they don't appear on the circuit diagram.
Perhaps a photo of the underside of the circuit board might help to augment the diagrams?
Apologies for my confusion, I appreciate your help. Steve

The downward pointing arrows indicate the ground connections for the Benedini and battery, which are common anyway.

Adrian.

Thanks Adrian. There does seem some thing intuitively wrong about connecting a 24v and 5v circuit together. Steve

You're just using the 5v circuit to operate a transistor switch on the 24v circuit.

There should be current limiting resistors for the LEDs in those diagrams - you don't want to be putting 24v directly across them

Adrian.

Adrian Harris wrote:You're just using the 5v circuit to operate a transistor switch on the 24v circuit.

There should be current limiting resistors for the LEDs in those diagrams - you don't want to be putting 24v directly across them

Adrian.

I used LEDs with built in resistors, voltage dependent.
Otherwise, yes, you have to use limiting resistors.