Products > Test Equipment

Capacitance substitution boxes

(1/3) > >>

watchmaker:
I am at the point where I want to vary capacitance in ckts so I am looking at substitution boxes.

I want one using 5% caps and decadal.  What are the "practical" choices for an amateur?  I see everything from 50 year old rotary dial boxes to $600 lab grade boxes.

Given I have the ST42, I can always measure the capacitance I think I selected.  Since it is used by an amateur, it does not need high life cycle switching (lab grade?).

THANKS

Dewey

tggzzz:

--- Quote from: watchmaker on September 13, 2024, 10:37:55 am ---I am at the point where I want to vary capacitance in ckts so I am looking at substitution boxes.

I want one using 5% caps and decadal.  What are the "practical" choices for an amateur?  I see everything from 50 year old rotary dial boxes to $600 lab grade boxes.

Given I have the ST42, I can always measure the capacitance I think I selected.  Since it is used by an amateur, it does not need high life cycle switching (lab grade?).

--- End quote ---

What is the required capacitance range and voltage and stability?

What is the allowable inductance? (Wires are ~1nH/mm)

watchmaker:
Thanks.  As you may know, I am an "innocent" when it comes to this.

I cannot see needing more than 30/50 volts.  I am thinking a range of 100pF to 1 uF should suffice.  At this point in my studies, I am playing with bypass and coupling in transistor circuits, basic filters and ICs like the 385 and timers like the 555/556.

I am following Boylestad/Malvino/Real analog and so basically trying to replicate a college curriculum.  If I outgrow the box, not a big loss; but that is unlikely.

Ease of use and a small footprint would be helpful.  I have come to appreciate the importance of capacitance in just about any circuit.

For L, I do not have enough experience to know how to respond to your request.  I am not doing much over a few 100 kHz and 30 VDC. Inductance is my next sequence.

I am jumping around a little with some active circuits, but nothing yet has had much to do with inductance other than transformers which I "understand" on a middle school level.  And I do understand EMF and electromagnetism, rt hand rule, etc. But that is about it.  Nothing with real analysis.

Regards,

Dewey

Phil1977:
Just to mention the cheapest solution that seems possible:

https://de.aliexpress.com/item/1005006235932003.html

Kean:
Models with rotary switches tend to be quite expensive, or they are old and require contact cleaning/repair.

I bought one with slide switches from Element14 (available from Newark in the USA), but it does require you to do a little math.  I also have the resistance version.  Fine for low frequency applications.

https://www.newark.com/tenma/72-7265/capacitor-decade-box-100pf-11/dp/22H6398
It can also possibly be found on Amazon or elsewhere by searching for TENMA 72-7265

Specs are 100pF to 11.111uF in 100pF steps, 50V max, 5% tolerance (+50pF max internal)

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod