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Electronics => Projects, Designs, and Technical Stuff => Topic started by: Mechatrommer on July 06, 2016, 01:35:47 pm

Title: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: Mechatrommer on July 06, 2016, 01:35:47 pm
curious...
when compared to original Bourns...
http://www.robotroom.com/Trimpots-2.html (http://www.robotroom.com/Trimpots-2.html)
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: calexanian on July 06, 2016, 10:40:46 pm
That is actually not too bad. I was expecting worse!
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: Vgkid on July 06, 2016, 10:51:40 pm
Thanks for pulling one apart. Actually not bad.
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: bitseeker on July 07, 2016, 04:33:01 am
Neat. The brush is definitely wimpier.
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: CJay on July 07, 2016, 08:42:27 am
Nice pics and doesn't look too bad at all.

Did you tear it apart because it failed (if so what was the failure) or just 'because'?

Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: Mechatrommer on July 07, 2016, 11:14:47 am
Did you tear it apart because it failed (if so what was the failure) or just 'because'?
no. just for fun, i still have some stock for that 200 ohm trimpot and i find it the least used part.  and i was curious on inductive effect of it. i guess not suitable for ghz range of application, similar to original Bourns since they are the same geometry construction. but on some of the other Bonens immitation that already in a circuit, i detected some discontinuity at some place usually set during operation, but not so serious for me to take it apart so far, a slight turn will get it back inline. i cant 100% blame on the components since its maybe my design is flawed, i havent analyze its heat dissipation spec.
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: Melt-O-Tronic on July 07, 2016, 03:44:11 pm
This is nifty.  I always wondered what happens internally when you hit the limit of travel.  Now I can see that, at least for this style, continuing to turn at the limit won't cause damage.  Thanks!

:-+
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: Fungus on July 07, 2016, 04:01:25 pm
This is nifty.  I always wondered what happens internally when you hit the limit of travel.  Now I can see that, at least for this style, continuing to turn at the limit won't cause damage.  Thanks!

I want to know how it comes back if you go past the end then start turning it backwards.

Doesn't that disconnect the gears?


Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: Mechatrommer on July 07, 2016, 05:24:43 pm
I want to know how it comes back if you go past the end then start turning it backwards.
Doesn't that disconnect the gears?
on the working unit, clicking sound can be heard while attempting to go past beyond the end indicates some sort of spring action that reverse the last teeth of the gear back inline, but i cant reproduce it on the teared unit. luckily i'm not inclined to know how it function mechanically, all i know is its working.
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: metrologist on July 07, 2016, 07:36:12 pm
I suspect the wiper is in spring contact with the end-point and pushes the gear drive together.
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: LabSpokane on July 07, 2016, 08:25:36 pm
I bought a grab bag of those to have for prototyping and they work OK, particularly for the price.  I'd run the Bourns for production.
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: mikerj on July 07, 2016, 10:26:33 pm
I'm guessing this was a pretty heavily used device?  There seems a be a lot of brush material embedded into the resistive track, and the brushes themselves look a little worn.
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: Mechatrommer on July 08, 2016, 12:21:51 am
I'm guessing this was a pretty heavily used device?
no, it only used a few times in a test circuit. most of the time ever since collecting rust. maybe that shows the low quality of the internal parts of it..
Title: Re: Destruction and Inside of MultiTurn 200 Ohm Bonens (Bourns Immitation) Trimpot
Post by: Fungus on July 08, 2016, 07:39:48 am
I'm guessing this was a pretty heavily used device?  There seems a be a lot of brush material embedded into the resistive track, and the brushes themselves look a little worn.

That might be from the disassemble process.

All the internal parts in those things are really soft so they make good contact. They're not built for daily use. Even the genuine parts are only rated for 200 turns.