reed switch

I've purchased the manual and am starting to gather parts. The manual lists a reed switch, but doesn't specify Form A or Form B. Does anyone know the correct type? I've written to the company but haven't yet received and answer.

adamsj3

Since I have not yet received any response from the Keppe motor group, this is my second request for information:


Mr. Castela-

Based on the statement that the manual for the Keppe motor contained all the information to build a prototype, I, in good faith, paid $50 for a copy of the manual. As I said in a previous email, the parts list does not specify a Form A or Form B reed switch, nor is it mentioned in the assembly instructions. I think this information is critical to the correct functioning of the motor. Please either supply this information, explain precisely why it doesn't matter, or return my money. Since one switch is NO and the other is NC, I can't imagine how they could be interchangeable.

Awaiting your reply,

Jack Adams

Hi,

Don't know the difference between a type A and type B but I used a Normal Open switch and my motor works.

I did receive a reply from the Keppe Motor organization. A Form A (NO) is the required type.

I hope this is useful for others trying to gather parts.

Hi all,

I have not been able to source such a physically large reed switch let alone a 3Amp reed switch. Can someone recommend a source?

Can the placement of the reed switch be further away from the coil than shown in the manual?

Also, I was wondering if anyone noticed that without the small NEO magnet for the reed switch that the rotor's field alone can activate the reed switch. Further, is the rotor's field interaction with the reed switch and the NEO's partial negation of that affect part of the control principle or is the coil supposed to get just a single momentary jolt per revolution and if so is it to attract the rotor to TDC or repel it out of TDC? What is the timing scheme supposed to be?

Thank you,

Greg

You can order the reed switch from Digikey (www.digikey.com). Hamlin has a number of 3A rated switches. They're sorted by the strength of the magnetic field required to operate the switch, specified in ampere-turns. The most sensitive they have in stock is DK part # HE517-ND, which is the Hamlin DRR-129 42-48. ($3.38 ea) I think I will order 3 pcs of varying sensitivity.

There are many good surplus stores in SoCal. Have you tried All Electronics (www.allelectronics.com)? There is (used to be?) a good surplus place on the right side of Hawthorne going S. from Rosecrans. Also, you could make good contacts at the TRW swapmeet if it still exists. It used to be last Sat. of the month. Check with local amateurs. shopeio.com used to have lots of goodies. I don't know if they have a walk-in location now. Even Fry's might have a reed that would work.


Jack

adamsj3 wrote:You can order the reed switch from Digikey (www.digikey.com). Hamlin has a number of 3A rated switches. They're sorted by the strength of the magnetic field required to operate the switch, specified in ampere-turns. The most sensitive they have in stock is DK part # HE517-ND, which is the Hamlin DRR-129 42-48. ($3.38 ea) I think I will order 3 pcs of varying sensitivity.

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Even Fry's might have a reed that would work.


Jack

Thanks Jack

Greg

gmeast wrote:

adamsj3 wrote:You can order the reed switch from Digikey (www.digikey.com). Hamlin has a number of 3A rated switches. They're sorted by the strength of the magnetic field required to operate the switch, specified in ampere-turns. The most sensitive they have in stock is DK part # HE517-ND, which is the Hamlin DRR-129 42-48. ($3.38 ea) I think I will order 3 pcs of varying sensitivity.
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Jack

Thanks Jack

Greg

Hi Jack,

Tell me if I'm correct here: I'm assuming we do NOT want a reed switch that is too sensitive because the one I used (to get my motor turning) was easily affected by the rotor's field.

And one other question: Are you far enough along with your motor testing to know what the timing scheme is supposed to actually be? My scope trace looks nothing like Figure A4 in the motor manual. Is a simple solid state exciter better than the reed switch in your opinion (or anyone else's ... please)?

Thanks in advance,

Greg

Greg-

It is correct that you don't want the switch affected by the rotor. I think that's why the shaft is extended as far as it is, so that the switch can be moved away from the rotor. Just speculation.

The "magic" in the Keppe motor and other similar designs, if it exists, seems to occur at the time of magnetic field discharge.....when the switch opens. The faster the circuit is broken, the higher the voltage.. V=L*di/dt. A solid state switch could be used, but the risetime from a mechanical contact is hard to beat.



Jack

Hi,

Enclosed are the results of a test where I mounted 2 switches on the motor instead of 1.
Compared to a single switch motor:
1) Torque is higher;
2) Energy consumption is higher;
3) rpm seems slightly higher.

Current seems to be approximately the same as with the single switch layout.

In this test, the switches were staggered 90° and mounted in parallel. I first tried 180° but that doesn’t work. To make that work you probably also have to switch the polarity on the coil but at this moment, I don’t have the equipment to do that.
In this tests, motor efficiency was not measured yet.

hi everybody,

I am searching for the reed switch for the last ten days each and every shop of our capital city but i didn't get it.

so, please any one suggest me to go for an alternate switching devices....

Hi,

As an alternative for the reed swich in the Keppe motor V1.0, there are several options. The webpages of http://www.simplemotor.com/ list some interesting ones:

1. Hall effect switch (example: see http://www.simplemotor.com/hemotor.htm , on the bottom of that page there is a link to a Reed swich motor example).
   
   
2. Optical switching circuit: this is used in the Keppe motor manual V3.0 (for sale at the website). Again http://www.simplemotor.com/kit7.htm provides some guidance. You might also use schematics of an optical pulse counter (for rpm measurements) for inspiration.
   

The simplemotor website doesn’t give you details about the components but with a technical background and some common sense one should be able to construct a working switching system. For other switching systems, have a look at that website, the details can be found under their “Assembly instructions” tab.
Although that simple motor has another working principle than the Keppe one, the schematics are quite similar (just replace their electromagnet by the Keppe motor coil).

Good luck.

Hi greef,

Thank you sir for you suggestion but luckly i got the Reed switch.
It was just ten rupees.


I made the frame for the coil winding with wood.
Now i want to use an iron rod as a shaft of 4mm diameter, how to make the magnets get attached with the iron rod. If i use any adhesives then the magnets rotation and the rod rotation will be same are not ?.
The dimensions of my magnets are
length 24mm
breath 44mm
thickness 10mm.

Thanking you.

any one suggest me to go for an alternate switching devices....