Spektrum CH3 Mod for Emaxx tranny.

[BrianG]

I did a mod to my Spektrum DX3 that may help those who also have this radio and want to use CH3 to shift gears...

Ever notice that the CH3 buttons on the Spektrum DX3 radio are momentary? If using for shifting gears in your transmission, you have to hold it in place. Also, the switch (labeled "A" on the radio) is kinda clunky to reach.

Well, I thought I'd add another switch so it wouldn't have to be manually held in place. This switch will be in parallel to the existing CH3 switch, so if you still want the momentary effect, it will still work - just put the new switch in the center position.

This (http://www.radioshack.com/product/index.jsp?productId=2062486&cp=2032058.2032230.2032278&pg=2&parentPage=family) is the switch I used. It has to be a SPDT (single pole, double throw) "center-off" type. "Center-off" means that the center position is totally "off", and either up or down is "on".

The existing CH3 switch is actually two switches with one common leg. You have to solder the center pin of the new switch to the solder point marked as "2" in the picture below. Then, the other two connections of the new switch can be soldered to solder points 1 and 3. Then, hook a servo up and try it. If it's backwards, just swap the wires on solder pads 1 and 3.

http://bgosselin.home.mchsi.com/spektrum/circuit.jpg

To use this feature, CH3 must be set to the "3P" (3 position) mode.

The switch needs a 1/4" hole to mount. I installed it so it could be easily switched using my trigger hand thumb.

A couple other picture of the actual switch wiring and final product:

http://bgosselin.home.mchsi.com/spektrum/wired.jpg

http://bgosselin.home.mchsi.com/spektrum/assembled.jpg

[F7GRT]

Very clean work, good job!

[BrianG]

Thanks!

This radio is actually used on a BL Revo and BL Jato, but I've been wanting to do this for a while. My first BL Revo used the emaxx tranny and I was going to use the two speed tranny, but found it was a PITA to switch the gears and keep it there. Since then, I've migrated over to the stock Revo tranny so this isn't needed anymore, but thought the emaxx crowd over here might find a use!

[BoysToys]

I just got the new version of that radio the DX3.0. The third channel has a setting just for the E-Maxx style transmission. Just push the button once and it will change gears. It is the black button where you rest your thumb. You are very brave to disect your radio like that. I am glad it worked out for you!
http://img.photobucket.com/albums/v218/BBates/XXX-TBrushlessGraphiteSpektrum00-1.jpg

[BrianG]

LOL, the internal circuitry is actually not too bad. The circuit board for the two lower switches are seperate so it wasn't a big deal, and there are no other devices on it except the switches and the connector that goes to the rest of the radio.

It's nice that the new ones come with an actual switch. I don't know why Spektrum didn't make their original version like that. :wacko:

Still, it's nice to have the option for momentary and latched CH3. Actually, you could mod yours so you have momentary switches, but it doesn't sound like you would want to do that with a brand new radio. :)

[BoysToys]

LOL, the internal circuitry is actually not too bad. The circuit board for the two lower switches are seperate so it wasn't a big deal, and there are no other devices on it except the switches and the connector that goes to the rest of the radio.

It's nice that the new ones come with an actual switch. I don't know why Spektrum didn't make their original version like that. :wacko:

Still, it's nice to have the option for momentary and latched CH3. Actually, you could mod yours so you have momentary switches, but it doesn't sound like you would want to do that with a brand new radio. :)
It actually has a seperate setting so you can use it as a momentary switch. You just have to chose which way you want it to work when you program it.

[BrianG]

It actually has a seperate setting so you can use it as a momentary switch. You just have to chose which way you want it to work when you program it.


Well, that's good then. They must have realized their blunder and incorporated it into the new design.

[Jeroen E]

This is very helpfull, thanks very much!!

[BrianG]

Glad you liked it! :)