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In my project I would like to switch between different resistors/capacitors on the fly, preferably without having to open the containing box around the PCB. Therefore, one idea was to use a jumper (connected via cables) which is placed on top of the box, which then can be used to set the currently active resistor/capacitor.
Are there other alternatives? I would prefer THT approaches, if possible.

The main aim of the circuit is to provide different R/C-constants for an OpAmp, operating at frequencies below 10 kHz. Switching between the different values should be as simple as possible, but still reliable, thus I prefer to avoid options mentioned like the alligator clips. Resistor values will be around 10k-10M, with voltages at +- 15V and currents < 1A. Cap values will be in the range of nF.

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  • \$\begingroup\$ Surely you need to decide how professional you want this to be. The answer could range from a pair of wires with crocodile clips on to fasten the capacitor to, all the way through to a touch screen LCD where you drag and drop the components. \$\endgroup\$
    – HandyHowie
    Commented Oct 11, 2019 at 9:04
  • \$\begingroup\$ A simple, but reliable way. As mentioned, a jumper selecting fixed resistors was one alternative I thought of. A rotary switch which selects the resistor/capacitor another? I only have to switch through three/four different values anyway. \$\endgroup\$
    – arc_lupus
    Commented Oct 11, 2019 at 9:07
  • \$\begingroup\$ @arc_lupus A rotary switch may be fine. It is considered expensive today. If you get a chance to look at a very old TV, circa 1970s or earlier, take a look at the tuner control. It was often not much more than a way to select amongst various passives used in tuning. It was considered the height of commercial professional methods then. Jumpers work. You'd need to say a lot more about your application and values, though, and something about the distances involved in wiring things up. Those olden days tuners required a lot of careful layout considerations. \$\endgroup\$
    – jonk
    Commented Oct 11, 2019 at 9:41
  • \$\begingroup\$ @jonk: I added some more explanation about how I intend to use the switch in my layout. \$\endgroup\$
    – arc_lupus
    Commented Oct 11, 2019 at 11:24
  • \$\begingroup\$ @arc_lupus More detail might be helpful. Such as the exact schematic details surrounding the opamp under question. Single-ended vs differential switching matters, at least to some folks, for example. The nF range of cap values is a "nice to know" as that can then be compared to likely trace capacitances. The range of resistor values does pose a concern, as you near 10 M, for some approaches. Though it is probably just fine (usually) for a rotary switch arrangement. \$\endgroup\$
    – jonk
    Commented Oct 11, 2019 at 22:58

2 Answers 2

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I am not so certain that there is a generic "best way" to choose between component selections. There may be a best way for your specific application and only you can determine what works for you. That said, there a multitude of ways that this can be done. Here are a few examples:

rotary switch

rotary switch

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dip switch

dip switch

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header with jumpers

header with jumpers

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alligator clips

alligator clips

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analog switch

analog switch

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digipot

digipot

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decade capacitor

decade capacitor

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fahnestock clip

fahnestock clip

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mechanical relay

enter image description here

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soldering

soldering

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  • \$\begingroup\$ This is giving a vague answer to a very vague question, Michael :-) \$\endgroup\$
    – TonyM
    Commented Oct 11, 2019 at 10:49
  • \$\begingroup\$ @TonyM - Is it less vague now? :^) \$\endgroup\$
    – Michael Karas
    Commented Oct 11, 2019 at 11:03
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    \$\begingroup\$ You forgot electromechanical relays. Since some of the resistance values are rather high, it calls for a solution that can provide high isolation. \$\endgroup\$
    – Dave Tweed
    Commented Oct 11, 2019 at 12:15
  • \$\begingroup\$ @DaveTweed - Added mechanical relay. \$\endgroup\$
    – Michael Karas
    Commented Oct 11, 2019 at 14:38
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A simple female header or IC socket to insert THT components would do nicely and won't limit you to fixed set of values. Plus it costs just a fraction of other solutions. Also, if you have an old breadboard laying around you can use that, as is or cut a piece of it.

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