There is one obvious way to completely avoid Taycol motor interference to the radio which is controlling it - use a modern 2.4 Ghz system. Any RF radiation from a Taycol is invariably at a far lower frequency, and even a cheap 2.4 Ghz will function with no disturbance whatsoever next to an completely unsuppressed motor.
However, note that RF interference carried through power leads may still disturb components like an ESC, and other nearby operators may be using lower frequency systems which are more prone to interference, so proper suppression should always be employed to avoid causing unwanted RF radiation.
Suppression is fairly straightforward - a 0.1μfd capacitor between the brushes, and a 0.1μfd capacitor from each brush to the frame. If there is still a problem, earth the motor frame and wrap the brush power lines around a ferrite ring.
If you want to know more about interference, here is a rather more comprehensive
discussion of the subject...
Modern radio systems expect to use an electronic speed controller (ESC) to operate the motor, and this usually reverses the input polarity to make the motor go backwards. As we have seen earlier, this will not work for a field-wound motor.
There are a number of ways of addressing this issue. The ones I know about are indicated below – if anyone knows of another method I would be glad to hear about it!
| |
Technique |
Advantages |
Disadvantages |
| |
|
|
|
| 1 |
use non-reversible esc |
Simple |
Provides no reverse! |
| 2 |
use external electrical switch, on an extra channel |
Follows original Taycol reversing advice |
Uses extra channel, harder to use ergonomically, and allows control to be switched directly from hard forward to hard reverse unless an interlock is incorporated. Needs extra mechanical/electrical work |
| 3 |
use reversible esc with added rectifier. |
Uses current technology, but involves modifying Taycol wiring. This is simple for persons used to electronics. |
Loses some power through the rectifier. Wiring may be tricky for persons unused to electronics |
| 4 |
use ESC-driven Switch Reverser |
Follows original Taycol advice. Uses latest technology. |
None apparent as yet |
1 – If you are just going to use a standard ESC, using a non-reversible ESC is more sensible than using a reversible one. A reversible one costs more money, and would give you a strange throttle control, with stop in the middle, full forward at one extreme of the stick and about half-forward at the other! In practice, having no reverse is usually less of a problem for a typical fast boat than it is for a slower scale boat, particularly something which does a lot of manoeuvring, such as a tug...
2 – Taycol instructions from the 1960s suggest adding a changeover switch. These were either going to be hand operated, or relay switches operated by the radios of the day, which demanded a degree of electronic knowledge to install. Modern radios are neither designed to operate hand changeover switches nor relays, but they can do this well enough if the operator is prepared to put in the mechanical and electrical work that is needed. Refer to the
Taycol Documents page for further information on changeover switch wiring. The actual installation will depend so much on the equipment used that there is no point providing further detail here, but the
Reversing Switch page has some suggestions for Taycol-style servo-operated changeover switches...
3 - A bridge rectifier (a fairly common cheap electronic component) may be attached to the Taycol motor in such a way as to allow one set of windings to be polarity-reversed when the speed controller reverses, while leaving the other set at the same polarity. A bridge rectifier is usually used to change AC into DC, where the incoming polarity is switched many times a second, but it will work equally well for this application. They come in several different patterns and sizes, but the connections are pretty simple. Go to the
Rectifiers page for further details...
4 – Recently, another option has become available, in the shape of a PIC microprocessor-controlled reversing switch from Action Electronics. This is a small unit designed to monitor a reversible ESC, and perform a mechanical action when it moves to 'reverse'. Mainly intended for mechanically reversing WaterJet boats or Steam Engines, it could just as easily throw the switch on a Taycol. Go to the
Reversing Switch page for further info, as well as some plans for Taycol-style servo-operated switches...
If you are adding reverse to one of these motors, be careful of the propeller and shaft connections. These motors have high angular momentum and high torque – slamming one into reverse can unscrew connectors or possibly shear the prop shaft.....
One reason that the Taycols have a reputation for being difficult to suppress is that, unusually, they require their brushgear to be regularly lubricated. That is what the small holes in the paxolin plates over the commutators are for!
Normal motor brushes must NEVER be oiled. Bit if Taycol brushes are not kept well oiled they will wear and start to spark badly. The result is often that old Taycols have a major problem with interference, which can be minimised with a few drops of oil onto the brushgear and commutator.
