Comments by Søren Kjær Nielsen

Electronic Speed Controls
Comments by Søren Kjær Nielsen

typos etc. corrected by EJB

From: "SKN" <skn@vip.cybercity.dk>
To: "Eric Behr" <behr@math.niu.edu>
Date: Wed, 11 Jun 1997 18:59:40 +0200

I have visited your homepage with Electronic speed controls. I have built some af the designs, and used them in my electric racing boats and my R/C aircraft. I have the following comments/hints about the plans:

Speed 400 controller, by Ulrich Dallman

The round construction is smart and fits nicely to a speed 400 motor, but I was not able to get it to function right - I have an interference problem; the controller was going into resonance when the motor started to use power. Have you been able to get it working ?? [EJB: no, I haven't tried that one] [EJB, 6/15/98: another person sent in a negative opinion about that unit] [EJB, 3/30/99: Barry Bickerton notes that the triangle wave generator is not hooked up to the comparator correctly. He suggests connecting pin 2 of the IC directly to pin 6, and not to R9. This requires modifying the PCB traces on the component side.]

Miniature speed controller by Josef Hoelzl/Milan Lulic

I made a new circuit board for smaller SMD-components (0805), with adjustable zero-point and max. trottle. The Speed 400 design by Ulrich Dallman gave me the inspiration: the new design is also round to fit the speed 400 motor.

I use the controller in my speed 400 racing boats, hence my circuit board is without the motor brake and the cut off components, but I have added a extra mos fet to get a smaller voltage drop (remember a seperate 100 ohm driving resistor) I have build more than 10 of these, it is a fine and stable design.

The Speed controler Mk2 by Ken Hewitt

(not your page - look at ftp://ftp.luth.se/pub/misc/rc/plans/electro) The computer controller constructed by Ken Hewitt, is good - I have made 2 pcs, both in my changed circuit board layout, with SMD (0805) components and without the brake and cut off functions. The new layout is very small: approximately 2 cm x 5 cm x 1 cm.

The unit is working fine, but it can give problems if the radio signal is low, and if the motor makes electric noise (I used capacitors, have changed timing and reworked/changed the brushes). The computer stops the controller if there is noise or no radio signal, and you have to trottle back to start again - not good for a racing boat... I am planning to use it in one of my aircrafts in the future.

Maxi Controller by Josef Hoelzl/Milan Lulic

I made a new circuit board for small (0805) SMD-components, with 5 power MOSFETs, but without the brake and cut off components (approx. 2 cm x 5 cm x 1 cm). I have 3 of these running. It a good and stable design (nearly the same as the Miniature speed controller)

To get better efficiency I have changed the plan. In the original the opamp is not driving the power MOSFET with complete square vave (either complete on or complete off - see description in Ken Kewitt article about the computer controller Mk2). I used Ken Hewitt's principle and added a special MOSFET driver between the opamp and the power MOSFET - it is working well, and gives nearly zero power loss, also with reduced speed. ( I still use a cooling plate to get high efficiency from the power MOSFETs). This controller is also made on a 2 cm x 5 cm x 1 cm board (nearly the size of the 5 power mos fets).

General

There are always new components coming out, and I have the following suggestions for upgrading the plans:

The double opamp LM 393 can be replaced with the CMOS op amp TLC272CD, which is more stable in the presence of noise on input, plus it can give full voltage on its output.

New MOSFET power transistors are appearing. I use the IRL 3803 now - it has a record low "on" resistance (0.006 ohm) and operates at logic levels, but can only handle 30 V maximum.

Happy flying (and sailing) - Søren Kjær Nielsen.