Group purchase of EPCOS B25839 MKV caps and TT maxon motors

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Group purchase of EPCOS B25839 MKV caps?


Bernhard has offered to get some of these caps and send them off. In order to save on shipping, I will handle the shipping out to the US/Canada. It should cost less about $10.00 each plus $3.00 shipping (padded bag $1.75 plus postage). Easiest way to pay is by paypal. I'd like to have all orders by next Friday.

So far, it looks like the 1uF/900V (600V?) is the cap of choice.

Best Regards,

Dale Herman (Paypal and email)
MKV B25839 & TT maxon motor, orders please!

### This is the order list ###
Status Wed 10/30/02, 14:10 CEST

where to get Siemens/Epcos MKV B25839 capacitors ?
where to get a decent maxon motor and a pulley for it?
Well, i have agreed to supply both at my cost. Please email me privately for your orders.

I get the maxon motor at our local surplus store; the motor will cost US$10 including any work i have on it e.g. for removing the gear wheel from the shaft without damage or glueing on the pulley.
I haven't got the prices for pulley yet.

Shipping from Germany is expensive; i recommend small package uninsured for $8 surface or $20 airmail. Insured parcel can go up to US$55 if airmail and priority is chosen.

This post is my bulletin board for collected orders. I will announce who has ordered and which quantity.

Consider folks, the 1µ is 20.5mm dia x 75mm length, the 0µ47 has same dia and 44mm length.

1µ0 / 700V:
dice45: 20x
RichardJones: 4x
setriode: 4x
PeterDaniel: 20x
kasra: 2x
Petter: 20x
GaryB: 8x
harvardian: 8x
AKSA: 4x
wiligruen: 20x

0µ47 / 700V ac:
dice45: 24x
setriode: 4x
peterr: 6x
GaryB: 8x
harvardian: 8x
AKSA: 4x

0µ33 / 700V ac:
dice45: 8x
setriode: 2x
Peterr :2x

0µ22 / 700V ac:
dice45: 6x

0µ1 / 700V ac:
dice45: 10x

order closed for all MKV and order placed today. I take all quantiies for granted. Within the next 12 hours i may be able to still increase ordered numbers, i.e. to accept additional orders.

maxon 2028.949-61.121-025
(48V for nominal 6440 rpm; the motor is NOS before i remove the gear wheel):

dice45: 5x
peterr: 3x
peted: 2x
Brett: 2x
gilid: 4x
planet10: 2x

maxon 2028.941-61.121-025
(36V for nominal 8850 rpm; the motor is NOS before i remove the gear wheel):

petter: 2x
dhaen: 2x
GaryB: 3x
difool: 2x
buglehead: 2x
infinite baffle: 2x

maxon 2028.945-61.121-025
(18V for nominal 8010 rpm; the motor is NOS before i remove the gear wheel):

pedroPO: 4x

(18 or 36 or 48V)

mgreene: 2x

2028.949 (48V/6440rpm): 18x, 0x left
2028.941 (36V/8850rpm): 13x, 0x left
2028.945 (18V/8010rpm): 4x, 0x left
some left, type not guaranteed.

I feel urged to tell you the motor diameter is 28mm, not maxon standard (26 or 29 mm). I recommended to put the commutator end of the motor in an airtight capsule. So this capsule will have dia 28, hinthint, better order one more as spare part, compared to maxon retail price list they are dirt-cheap.

All different motors behave as expected; samples has been tested with success.
orderlist for motors may be still open for a few more; a second lot showed up. But i will not guarantee which one will come, anyhow i will not mix it up with orders already placed.

dice45: 3 kits
peterr: 1 kit
peted: 2x
Brett: 2x
gilid: (4x)
ultranalog: 4x
petter: 1 kit
planet10: 2x
dhaen: 2x
GaryB: 3x
buglehead: 1 kit
infinite baffle: 1 kit
pedroPO: 1 kit
difool: 2 kits
mgreene: 2 kits
Variac: (no quantity specified)

Effective diameter will be 12 mm. To allow for different shaft diameters and to enable mounting free of brute force and to ensure proper concentric running, i have decided to go with a collet chuck clamping for the pulley. This means: should the motor be faulty, noisy, simply worn, the pulley can be recycled for another motor without damage for both motor and pulley. Pulley will have a collet chuck for 3mm and for 2mm with it.

I am considering to make separate pulleys for flat belt (e.g. magnetic tape) and round belt (big o-ring or string) fitting on the same collet chuck.

the collet chuck solution is what i settle on; I got no objections.

I also settle on separate pulleys for flat belt and round belt; in fact one pulley kit per person should be sufficient, maximum two if some of you want a replacement kit.

Option: pulley with roughened run surface for voicing (some may sonically prefer a smooth and slippery pulley and others a rough and slip-free pulley)

Delivery time depends on the pulley.
I hope to have access to CNC machining for the pulley within 3 weeks from 10/18/02. Sorry, my buddy is behind schedule. I am pushing him everyday but i am not making promises concerning the schedule.

120 Hz Strobe flasher, quartz crystal stabilized, complete with housing:
dice45: 1x
hifidaddy: 1x
peterr: 1x

120 Hz Strobe flasher, kit with perforated PCB:

Still wondering if others than GaryB have read my posts conerning the strobe flasher.

B25839 come as 0µ1, 0µ22, 0µ47, 0µ68, 1µ and Bürlkin and Epcos specify them "for coupling purposes".
For bigger values you have to parallel them or use B25834, these group to 10µ.

And, do not misspell my name, it is fully sufficient if i do it. Misspelling my name, i mean :)

do you want to handle shipping only or also payment issues (i.e. you place a collected order for all and i charge you total)?

Hey, and let's put a two week schedule on it, it is holiday time. :)

i have intended to use closed my thread as order announcement. But i did not want to move too much air around our group purchase. I have a bad feeling seeing 3 threads now around the topic and noone know where to look 1st.
Therefore I merge my post/thread now with this thread.
i misspell my own name all the time :)

I haven't tried '34 and '39 in direct comparison, i only know that '34 always were used as top notch coupling caps for larger values. Tube application, 100's of Volts across it. My buddy Peter Hartmann's fabulous 845 SET amp is MKV '34 all over. PS and couling caps oops, there he used some '35.

I once tried one as speaker cap, just fabulous. I already tried the as tubeamp PS caps, best you can get. But i doubt that such a big device can equal the '39, i always found smaller physical size to be preferred sonically, all else conditions being similar.
Parallelling '39 is expensivish but would be my preference. Slight preference.

10µ of MKV '34 is a medium size eggshape hand grenade. Derating is fancily ridiculous. A 33µ /600V MKV slowly started to cook and die at 1600V.

For those wondering what the MKV hype is all about, follow the WIMA MKS vs.MKP thread
Hi Richard,

As the shipping charges for each individual person in the USA/CA would be around $16.00, I was going to have all USA/CA orders shipped to me and I would re-ship out. The price for the re-shipping would be around $2-3. ea.

Lets assume there are 6 people in the USA/CA interested:

Shipping: 16.00
Re-ship: 6*2.5 = 15.00

Total $30.00/5 = $6.00 each person, savings of $10.00

It may be easiest to send me all of the payments and I will pay Bernhard, thus eliminating the confusion in shipping charges.

Bernhard and I have agreed to wait two weeks before finalizing the order.

Best Regards,


P.S. Please send all queries on what's available to Bernhard. I am only handling the USA/CA redistribution to save us some money.
Hi Peter,

In my line of work (designing and building automation equipment), we use lots of brushless servo motors to move things around. We have been buying Micro-Mo motors and these are very expensive (600-1000 US). These motors are quite small, but can spin very fast 12000 RPM. Usually, we gear them down.
I have a Maxon motor in my hand right now that I got as a sample. The motors are built extremely well and are a steal at Bernhard's price. Of course, there is not much application in the DIY audio world (motorized pot not withstanding).

Best Regards,

visit us at the "let's make a DIY TT" thread and then ask this Q again.

Of course you can and the type i have selected has sleeve bearings, not ball race bearings and finger commutators made from precious metals. And who if not you is able to make a neat little adaptor flange :)

But after you are intoxicated with concepts on DIY TTs, i doubt you build it into your MapleNoll. Hmmh, maybe you order enough for the MapleNoll **and** your new diyTT :)

The maxons are voice coil motors with 13 overlaying windings (and the commutator is separated to 1 sections accordingly) so torque ripple is practically zero and the motor starts smoothly turning at 300-500 mV. The surplus shop i get the maxon from has many different types surplus. If you specify voltage, it well can be they stock it and i can send it.
Obsolete soon!!!!!!!!!!


I just talked to a EPCOS rep. He mentioned that the whole B25839 is on its LAST production run for a customer and will be withdrawn after that.

You may want to check with those 2 companies that sell them if they have any still in stock.

I can get MOQ of 90 pieces at an undetermined price from EPCOS if this is true and anyone is still interested.

Granted.... 90 pieces is a lot!!!

Epcos rant

i am not supposed to use the language i would like to use now ... those stupid green table globalizers at EPCOS!! :redhot:
They have a rock-solid brand, Siemens, and they have long-term customers. A big heap of the MKVs goes into the German Intercity Express high velocity train. And what to do they do, fiddle around with the stock market, dump their brand name, mess up customer relations. I have buddies working there, they report a steady slope downwards business-wise the last few ys.

Tomorrow i go to Bürklin and inquire how much is left there.
Recently i bought a lot of 120 MKV B25834, hope they last for my projects.
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