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multi-position switch electronically controlled?

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neazoi

neazoi

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Toggle switches can be easily made and electronically controlled using relays or transistors.

But what about is someone wants to make a multi position switch?
Is there any technique to minimize the amount of relays?

Any examples/schematics would be appreciated.
 

I am affraid that the solid state devices will introduce their own characteristics into the circuit, like resistance, capacitance and they may behave as mixers in RF, that will totally alter the characteristics of the circuit.
A pure capacitance would be just a passive capacitor. but to switch more than one capacitors moltiple switches or relays are needed. Is there any other way that does not affects the characteristics of the capacitor?
 

It will help others make appropriate suggestions if you provide more info about the kind of application you had in mind.
 

I am trying to electronically alter the capacitance in a specific point in an analogue circuit, for example an HF oscillator. A varicap is not the solution I look for.
A switched capacitance bank could be one solution, but multi switch relays are needed
 

Binary 8/1 Multiplexer with 3 relays....

1_8_Relay_Mux.png
 
If you're going to switch capacitors in an HF circuit, presumably the caps will be of low value. Electro-mechanical relays and the associated wiring will introduce their own effects which may not be negligible.

In any case, the relays could be used in some form of binary combinations to provide more different cap values than the number of individual relays. Two relays will give you four different combinations, three relays - 8 different cap values, and so on. It shouldn't be difficult to work out the control logic.

Added on editing:
Ah, I see that kak111 had also come up with the same suggestion but was quicker on the trigger.
 
Last edited:

Thank you.
I consider using these DIP reed relays. They are of very low profile and their small size and the reed construction should minimize inductance.
 

There are appearing a number of tunable capacitor
technologies. Digitally switched capacitor banks are
among them. Mostly sized for cell phone antenna
matching apps, so you'd have to like a few pF total,
a couple tens of pF tops, and a relatively low bit count.
The switched CMOS+MIM types have no need for the
high bias voltage of a MEMS, PZT or PIN diode type.
 

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