Made some mods to the horn. I was getting a bit of interference with the servo mod and the engine sound speakers. So out with the modified servo board and in with a Pololu RC switch low-sid MOSFET. Very nice unit. Super cheap and super easy to use. It is programmable, but not necessary with a Spektrum Tx. Servo freq. worked fine as already set in the RC switch.
I had to create a pull to ground to fire the sound board as explained above, so this was done by using the two NEGATIVE side solder lugs on the board. One is connected to the yellow wire for the wt588d trigger, and other one connected to common ground for vehicle. ALSO, you will need to solder the power jumper on the RC switch if using one power source. The blue LED is now unhooked as it ran off the servo board. Everything else stays the same, including 5v regulator to power amp and sound board.
Added an FPV cam to the D100. It's located on roof of passenger seating area. Hood mounted tire is a bit in the way but you get used to it..... Good view in the dark. I used an eachine ev800d with built in DVR. Worked fine after formatting the microSD card to FAT32 and 'automatic' and giving it a very short name. NOTE: the vid is recorded in .avi and the sound does not play on all movie players. Much on the net about the sound not recording, but it works fine on headset playback and using windows media player. Sound is terrible, but I will eventually redesign the Tx built in mic which may be the issue. If it is in the headset board, then that will not be fixed. Video is very good for the most part, and frame rate is very fast. No hesitation when recording and a fairly steady picture for being bounced around on the ground! Only drawback so far is that the on screen 'battery' indicator is NOT accurate at all. Comes with a nice 12v 500ma wall charger. Supposed to get ~1 hour of run w/record time on the built in battery.
See videos:
https://www.youtube.com/watch?v=jQlRjlMw8IE
https://www.youtube.com/watch?v=jzyQUeXktjw
Lots of wires...long time to get all configured...Clover antenna for video Tx. Folds down when not using. Camera is not too obtrusive. I plan to put a few on my RC boats. The horn really is just perfect for this scale. Sound is loud and clear, much better than in the vids. I also added 'Main' and 'camera' on/off switches. 'Main' powers all the ancillaries, and 'camera' just powers the camera. One major reason I chose this particular camera/Tx combo is that the cam and Tx are separate and easily remotely mounted from each other. There is also a ~3" extension for the antenna, making mounting it much easier. Finally, the cam and Tx run off another Pololu 5v 2.5 amp voltage regulator hidden with the Tx in another little 3D printed black box on rear corner of roof.First pic is camera and Tx and 5v regulator in black tape. Next is the horn unit with new pololu RC switch. Final pics show the video Tx antenna and new back up spotlight.