I have decided to stick with the ztron timer but I am unsure which version I want.
ZTRON CL TIMER CLT4 v1.0
ZTRON CL TIMER CLT3 v1.0
ZTRON Simple CL Timer
I am unsure of the differences between them other than price and have been unsucessful in finding any information on them. 

I mostly build smaller planes but I am working up in size.  Someday the shark 45 I have unbuilt will be e powered. 

Here is a list of capabilities of the simple timer:

The CL timer/sequencer is a small lightweight board (1" x ¾", 2 grams), with the following features,

1) Adjustable flight time from 0 to 8 minutes by turning a small potentiometer. There is no way of programming an exact flight time, only trial an error will give you what you want.
 
2) Adjustable motor RPM by turning a small potentiometer. There is no way to program and exact motor RPM, trial and error will give you what you want.
 
3) This timer is aimed at beginner fliers because there is no programming. The draw back is it is less accurate.
 
 
 
Here is a list of capabilities of the V.3:
 
The CL timer/sequencer is a small lightweight board (1" x ¾", 2 grams), with the following features,

1) ESC (Electronic Speed Controller) controller and timer for your CL flights to a selected duration from 10 seconds to 10.5 minutes in 10 second steps. It will work with brushed or brushless ESC motor controllers.
 
2) Programmable starting and ending speeds, from full-off to full-on and anywhere in between.
 
3) Landing Gear servo output for slow realistic motion (active only for selected flight duration over 2 minutes).
 
4) In addition to the landing gear, three motor blips warning the pilot about the end of duration can be enabled.
 
5) Programmable motor starting time, from 0 to 10 minutes.
 
6) Timer shipped with default (standard) parameters. Default parameters can also be programmed in 1 step.
 
7) Soft motor speed ramp up and ramp down to conserve the motor gears and avoid excessive current spikes.


 
Here is a list of capabilities of the V.4:
 
The CL timer/sequencer is a small lightweight board (1" x ¾", 14 grams), with the following features,

1) ESC (Electronic Speed Controller) controller and timer for your CL flights to a selected duration from 10 seconds to 10.5 minutes in 10 second steps. It will work with brushed or brushless ESC motor controllers.
 
2) Programmable starting and ending speeds, from full-off to full-on and anywhere in between.
 
3) Landing Gear servo output for slow realistic motion (active only for selected flight duration over 2 minutes).
 
4) In addition to the landing gear, three motor blips warning the pilot about the end of duration can be enabled.
 
5) Programmable motor starting time, from 0 to 10 minutes in 10 second steps.
 
6) Soft motor speed ramp up and ramp down to conserve the motor gears and avoid excessive current spikes.
 
7) Timer shipped with default (standard) parameters. Default parameters can also be programmed in 1 step.
 
New to V.4 is the external potentiometer for fine speed adjustments before each flight and an external switch harness for Timer power and emergency shut offs. The external pot provides 24 fine speeds (about 40RPM steps), 12 on each side from center (detent). This resolution is 5 times finer than the standard programmable start and end speed steps. The last pot position will be in effect on the subsequent flight.
 
9) Revision 1.1 adds programmable blip motor speeds for better motor blip detection.
 
10) V.4 adds 90 degree servo pins for easier mounting.
 
11) V.4 adds a plug and play switch harness that requires no soldering so you are able to turn the power On/Off to the timer only. (a kill switch in the battery circuit is still recommended).


Mike

I try to keep all Z-Tron products in stock 24/7/365. I know there are others who do as well.

Mike