Walthers oilwell pump speed

Just put a resistor in series with the motor power, just like with your train power and it will slow down. The alternative is to use a voltage regulator for a stronger more constant speed.

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Hello

A taper-wound resistor/rehostat would work and >Is this a trial-and-error process to determine the size of the resistor

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Or you could measure the voltage drop across that resistance and use OHM's Law to calculate it.

I think the correct answer is a rheostat (aka variable resistor) '-). If you are powering it from a regular DC power supply, like a cheap transformer you got with one of those Bachmann train sets, (I've got about 6 of 'em now), that works, too.

If you are using a constant voltage DC supply, you could also just pick up a bunch of resistors and try them one at a time until you get the right speed. The question is how much current the motor draws: amps * volts = watts (VA), so you know the resister power requirement. The resister generate heat from the power is soaks up, and too small a resistor will get too hot.

Ed

in article snipped-for-privacy@news.ruraltel.net, harrym at snipped-for-privacy@ruraltel.net wrote on 3/7/05 7:17 PM:

I don't know about the Walthers motor, but Faller has made an oilwell pump and slow motion motor. Faller's motor uses an unusual design, a disk wheel with ramped ridges runs against a pair of furry brushes with a pair of coils behind. This motor would run at 120% of the European speed in the US. Lowering the voltage would work to reduce speed, but only by reducing torque and reliability. A diode would give half wave pulse power which should work, with some reduction in torque. It's quite possible that Walthers uses the Faller motor.

Tamya make several motor/gearbox combinations where the gearbox is of good quality, which could be mounted under the baseboard and drive throufh pulleys and rubber band drive. The gears are stackable so any ratio is possible. The Tamya mechanisim (I have) is "busy" at full voltage but quiet at half voltage. The motor is a cheap $1- can type but the mounting is a simple round socket and clip around the motor so any equal sized can could be substituted.

Regards, Greg.P.

I doubt that Walthers uses this unusual motor.

It sure is a peculiarity though. It's actually an odd form of stepper motor. The electromagnet intermittently pulls the driving disk down against the oriented nap of the fur, which then pushes it back up while imparting a very slight rotation, ratchet like. Repeat at 120 Hz. for more-or-less continuous rotation, at perhaps 3 or 4 RPM with NO gear reduction (and a soft buzzing vibration). Torque is slight, but sufficient to animate some things. It's like propelling yourself across a carpet by just shifting your weight from one foot to the other, but NOT lifting or sliding your feet.

Dan Mitchell ============

Two formulas that you have to deal with for a fixed resistor. V = I * R P = I * E where: V = voltage in volts I = current in amps R = resistance in ohms P = power in watts. The motor is probably drawing about 0.5 amps and you probably want a voltage drop of about 6 volts so you will do the first formula which is: R = 6V / 0.5A or 12 ohms. The second formula is then used which determines the wattage rating of the resistor: P = 0.5A * 6V or 3 watts for the resistor. About double that so the resistor doesn't get too hot at a minimum which means that a 5 watt resistor will work Now for some fun! Resistors in parallel will decrease the total value of voltage across the resistors. Thus, if you use two resistors of twice the value above in parallel, the resistor wattage rating can be halved without any problems. Resistors in series will double the voltage across the resistors so you could also use two resistors of 6 ohms and half the power rating again. The two aboce rules also work when you use more resistors. 3 resistors mean triple rather than doubling of the values and so on. A string of 12 1 ohm resistors will mean that you can use 1/2 watt resistors for the same rating. I'll note that until you get to large wattage (over 2 watts) resistors are available in standard resistance values (1, 1.2,1.8 ,,, resistance values) while larger ones sometimes follow those values but often are in other resistances. The resistors are also rated with different percentage ratings of variation of the resistance value so a 10 ohm resistor with a 20% rating amy only be a little over 8 ohms of actual resistance. Thus, don't worry too much about getting an exact value on the resistor as you can always adjust the voltage drop with the addition of more resistors in the string. Thus it is better to get a number of 2.2 ohm resistors and put several in a string to get the speed you want of rht e oil pump.

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If you've got that kind of motor, the change in voltage will still make a speed change although the change won't be as large. There was a slot car setup that used those kinds of motors and they worked well enough but didn't have that much of a bottom end for speed.

-- Why isn't there an Ozone Hole at the NORTH Pole?

Hello

Seem to remember the Faller motor as being AC. The ones I have run on 14 -16 volts AC.

I thought they juist spun round though, >If you've got that kind of motor, the change in voltage will still make a

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Assuming the motor is DC --

High tech solution - Build an adjustable power supply using an LM317 voltage regulator to control the voltage to the motor.

Low tech solution - Add 1N4001 diodes in series with the motor until you get the desired speed. Each diode will decrease the voltage by about 0.7 volts.

Rob.

Model Railroad & Misc. Electronics -

For those not turned off by formulas, but who are trying to understand, and haven't figured out from the example: V = E in the above equations. That is, V and E both refer to voltage.

OOPth, I normally use E for voltage as that is the industry standard way for electiconics but used V instead as this is often more "understandable" for the neophyte electrical person. E, does indeed mean V in that formula. Proofreading the post before sending it failed to catch that silly error.

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I think that EE use E for voltage, physicists use V for voltage, at least as I remember my college physics and a couple of web sites I looked at.

The EE site (

Ed

in article snipped-for-privacy@news-1.nethere.net, Bob May at snipped-for-privacy@nethere.com wrote on 3/9/05 12:28 PM:

Whoops: extra parenthesis. The physics site is

in article BE54A444.8A13% snipped-for-privacy@unearthlylink.net, Edward A. Oates at snipped-for-privacy@unearthlylink.net wrote on 3/9/05 1:01 PM:

Harry, if you don't want to bother with calculations, the best way is to use several diodes in series with the motor. Simple 1amp diodes (anything in the 1N400X series - like

Each diode drops about 0.7V (almost independent of the current). So if you wire 10 diodes in series, they will drop 7V across them. If your supply is

If you want to go with the variable resistor route the problem is that it needs to be high power and fairly low resistance (probably like 100ohm or less). Those are hard to find in places like Radio Shack. It would have to be wirewound pot.

Try the diodes - you'll like the results.

Here is the schematic (I hope it is readable).

Diode -!>|- (the > points towards cathode - the stripe painted on the diode case). (+ )the power supply positive (-) the power supply negative

(+)

--!>|--!>|--!>|--!>|--!>|--!>|--!>|--!>|--!>|--{motor}-------------- (-)

Peteski

It is actually an AC synchronous motor (will not run on DC at all).

Somewhat similar to the motors which were used on the old analog electric alarm clocks.

Its rpms depend on the freqency of the supply. It will actually run a little faster in US than in Europe (as US uses 60Hz and Europe 50Hz). If you are really crazy you could build a variable frequency power supply to control it's rpms!

This is getting OT though... And it would really be nuts to do this.

PEteski

Going to Radio Shack tomorrow [112 miles] and will get the Radio Shack