Hi just working on my Swift 16 Battery Raikcar, this came second hand from RM Forum and has these 3 gizmos wired in parallel with the motor. If you cant quite read the Txt it says 10A 100v. If needed can I manage with just 1?
Any idea what these do please and why are there 3 of em?
- Thread starter dunnyrail
- Start date
The Shed
Citizen of the Republic of the North East.
104 Capacitors for electrical interference protection from the motor to the on board electronics.
Best guess, if the original owner has fitted three, may well be a very noisy motor electrical wise, although saying that, the way they are connected is ineffectual in reducing the noise element.
Remove them, try and see, if problematic, put two back, one leg to each motor terminal, join the remaining pair of legs and solder to the motor casing.
Best guess, if the original owner has fitted three, may well be a very noisy motor electrical wise, although saying that, the way they are connected is ineffectual in reducing the noise element.
Remove them, try and see, if problematic, put two back, one leg to each motor terminal, join the remaining pair of legs and solder to the motor casing.
Brixham
No buffers were hurt at this sign
These look very much like disc ceramic capacitors intended for suppressing motor electrical noise. Why they are wired in series??? If they are rated at 100v then all 3 could be in parallel if the motor is lowish voltage ( under 10v ). Transient voltage spikes can easily be several times the nominal voltage going to the motor, which is why 100v devices are present. The 10A marking? I would think this capacitor would be 100pF, or 0.1 nF
If you’ve got room for them, leave them as is.
Malcolm
If you’ve got room for them, leave them as is.
Malcolm
As has been said, they are ceramic disc capacitors, but the '10A' marking is actually '104' and means the value is 100,000pF or 0.1uF. The 100Volt rating seems rather high for the intended use, when 50V would be more than adequate. There's no need to connect 3 in series as shown, the correct connection is one from each brush to the case, with the third one just connected across the brushes.
G.
G.
Greg Elmassian
Guest
pretty dumb, maybe the manufacturer was out of 0.01 mfd, usually a better value.
since they are in series, then you have 1/3 of .1 mfd, or 0.33 mfd, which is probably a better value than a single 0.1 mfd cap.
the capacity is related to the FREQUENCY of the noise you wish to supress... i.e. it becomes a tuned circuit with the motor and will appear as a short at certain frequencies, thus supressing the voltage going down wires and radiating interference.
voltage ratings on capacitors are ALWAYS over the nominal voltage, and remember what is to be supressed is NOT the voltage the motor it is being driven with, but the electrical noise GENERATED by the motor, which includes BEMF voltage which is ALWAYS higher than the operating voltage.
This is pretty standard stuff on all electrical motors.
These "noise caps" have been on motors for years, but perhaps the main question is why not one, instead of 3, and it's probably what they had lying about or was cheapest.
ugly, and the longer leads defeat some of the purpose, clearly not designed by an electrical engineer, would not be approved in the USA by regulatory agencies.
Greg
since they are in series, then you have 1/3 of .1 mfd, or 0.33 mfd, which is probably a better value than a single 0.1 mfd cap.
the capacity is related to the FREQUENCY of the noise you wish to supress... i.e. it becomes a tuned circuit with the motor and will appear as a short at certain frequencies, thus supressing the voltage going down wires and radiating interference.
voltage ratings on capacitors are ALWAYS over the nominal voltage, and remember what is to be supressed is NOT the voltage the motor it is being driven with, but the electrical noise GENERATED by the motor, which includes BEMF voltage which is ALWAYS higher than the operating voltage.
This is pretty standard stuff on all electrical motors.
These "noise caps" have been on motors for years, but perhaps the main question is why not one, instead of 3, and it's probably what they had lying about or was cheapest.
ugly, and the longer leads defeat some of the purpose, clearly not designed by an electrical engineer, would not be approved in the USA by regulatory agencies.
Greg
Greg Elmassian
Guest
Yeah, but usually 3 are:
1 between brushes
2 more from each brush to the motor case/ground
This is a case of not having the right value, and a poor implementation with the extra lead length, reducing effectiveness and radiating more noise than necessary.
Greg
1 between brushes
2 more from each brush to the motor case/ground
This is a case of not having the right value, and a poor implementation with the extra lead length, reducing effectiveness and radiating more noise than necessary.
Greg
PhilP
G Scale, 7/8th's, Electronics
Looking at the way they have been connected, and the bits of sleeving, I would say they were originally across the motor, and each end of the windings to the can..
My guess is that 'something else' was removed from the model (before putting it up for sale) and things just bodged-together?
PhilP.
My guess is that 'something else' was removed from the model (before putting it up for sale) and things just bodged-together?
PhilP.
Greg Elmassian
Guest
If they were originally soldered as suggested in post #7, you would see solder blobs on the motor can, can't see any in that picture. (a more complete set of pictures would settle that).
Also the leads would be shorter... those honestly are terrible solder joints. First rule of soldering is the joint should be mechanically strong BEFORE soldering, those 2 lap joints are a big no no.
But the errant bits of heat shrink could support your theory, I agree.
Greg
Also the leads would be shorter... those honestly are terrible solder joints. First rule of soldering is the joint should be mechanically strong BEFORE soldering, those 2 lap joints are a big no no.
But the errant bits of heat shrink could support your theory, I agree.
Greg
Thanks for the answers all, I think that setup was originally the as G said in post 4, likely the connection to power was either side of the thing central thingamybob oh sorry capacitor. So by the sound of things I should solder 1 between the 2 terminals on the motor and then wires from those same terminals straight to the power supply? As this will be powered via a Piko setup I think that may be prudent though I have not had any capacitor on my test setup of the Piko system and it worked just fine.
Greg Elmassian
Guest
Are they necessary? Well here in the US we have laws/rules about noise emission, so if that was sold in the usa, it would be fitted with noise suppression devices more extensive than you see there.
But does it make a difference to you in your house? I have never seen it be a problem unless you are running shortwave or AM radio.
Some older DCC decoders (I know this is not DCC) go nuts with noise supression devices.
All of mine are gone on my locos.
Greg
But does it make a difference to you in your house? I have never seen it be a problem unless you are running shortwave or AM radio.
Some older DCC decoders (I know this is not DCC) go nuts with noise supression devices.
All of mine are gone on my locos.
Greg
I suppose in these days of digital tellies and things, is less of a problem than before.
Greg Elmassian
Guest
The capacitors are to protect OTHER equipment from electrical noise from your Railcar. If you notice any difference it will be from interference to other devices.
Greg
Greg
GAP
G Scale Model Trains, 1:1 Sugar Cane Trains
All my Bachmann G locos had them before I converted them. My HO stuff had them till I went DCC.
Greg Elmassian
Guest
Yep, standard issue on Bachmann here in the US, would find it hard to believe that it was removed for the European market, which is normally MORE restrictive in terms of EM interference requirements.
Greg
Greg