RC Tanks Australia Forum

Want to know how to shoot longer and harder, IR that is... Well read on....

With the release of the MAKO a lot of people straight away asked for a Heavy Tank version that could take more than the standard Heng Long's 5 hits. Not a problem... A simple update of the MAKO's firmware can allow 9 hits before your Heng Long is 'killed'. But this got me to thinking about all the other advantages of rolling around the countryside in a KT rather than a Pz III. One of the biggest advantages must of been been the increased gun range. Can this huge advantage be brought to the IR battlefield?

Theoretically, it can by using a higher power IR emitter just the same as using a higher power cannon. Normal LEDs have increased in intensity so much in the past few years that they bloody hurt when you look right at them. Well so have IR emitters. I may be wrong but it seems likely to me that the IR emitters used in both Tamiya & Heng Long tanks are 'out of date' specifications wise. Upgrading to a new model IR emitter should provide you with an emitter with greater radiant power and intensity.

IR Emitters vs Standard LEDs:
Before going any further a quick word on IR emitters vs standard LEDs. Any of you who have done ANY work with LEDs know that 99% of the time they will require the use of a current limiting resistor. A standard LED requires around 20 milliamps for operation. Because they are switched on/off rapidly for short periods of time IR emitters can handle up to 1 AMP. The more current you push through them the greater the intensity. In most cases the relationship between intensity and current is as below:



The solution is therefore obvious – chuck more current through your new high power IR emitter

PROBLEM:
Simply swapping your old IR emitter for a newer model probably won't result in any noticeable effect. Why? Because the HL or Tamiya circuit is only supplying enough current to run the emitter it was designed for. You may see a slight improvement due to the increased efficiency of newer emitters but it is unlikely that you will be able to take full advantage of your new emitter. This is because the amount a current 'available' is limited by the circuit design.

SOLUTION:
Modify the Heng Long or Tamiya circuit to give more current to your IR emitter. Simple in theory but much harder in practice (damn near impossible if the circuit is Surface Mount Technology). So I guess this is as far as you can go. Unless of course you have a Mako or Whaler.
Both the Mako and Whaler have 'full control' over the IR emitter circuit. The Darlington transistor allows the high current, rapid pulsing required for IR operation and current limiting is done by the 10 R resistor. 10 R was chosen for these units so that the emitters used by Heng Long would not be damaged by higher current pulsing through them.

If the standard Heng Long IR emitter is replaced with a new extra high power and intensity emitter and the 10 R resistor replaced with lower value resistor then 'theoretically' a greater range over the IR battlefield will be obtained. Several newer IR emitters are being tested with limiting resistances of between 2 to 5 ohms. On the oscilloscope the performance of the new emitters looks outstanding (they even make my crappy oscilloscope look good). How this relates to field tests? Well I'll guess you will have to come back for the results.......

FFeF
Finally the Fan eFfect – Ok so if the high powered emitters work what is to stop one tank sitting at the end of the battlefield from shooting and hitting everyone within a square mile? Well... nothing really. However, with the advent of high power emitters we also see a significant narrowing of the angle of half intensity. In plain English a narrower beam. I'm not a big fan of rules but if one was to use a new high intensity emitter then selecting an emitter with the narrowest angle would be the most 'gentlemanly' thing to do. Hence the emitters under evaluation have the beam angles of 10 degrees or less. Like the data for the emitter below.

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