very small mechanical latching relays

Do they make very small mechanical relays(for switching very small currents
and voltages) that also latch?

Essentially I need a way to switch analog audio signals using a
"non-envasive" method... which means no semi-conductors(theres a reason but
don't bother asking... just assume its impossible and don't try to give
reasons why it should matter cause I already know them).

Obviously the coil is the issue but since the currents and voltages are very
low I assume that the conductor for the switch can be small also and
therefore one doesn't need such a large coil... or maybe theres some other
mechanism for switching that could be used...

What I want is for the switch to latch in the on or off state and need any
power to hold that state. I believe this could be accomplished with springs
or some other method of producing just enough friction to hold the switch in
place.

Any ideas?

Thanks,
Jon

 

"Very samll" is not a dimension, but yes, they make small,
magnetically latched relays with two coils. A pulse to one
coil latches the relay, and a pulse to the second coil
unlatches it.

We need actual specifications, if we are to find you something.

Here are some examples:
http://pewa.panasonic.com/pcsd/product/sign/pdf_cat/sx.pdf

 

a few volts which problem on average is < 1V(actually about 100mV on
average) and the current is in the mA range if not smaller but probably
smaller.

I was hoping something a bit smaller than 1/2". I would be using a lot of
these and the smaller the better.

The idea is that I want to switch a couple of components into various
configurations using a digital method instead of mechanical... right now I
have 3x8 dip switches to do the switching and it requires that I change all
the switches by handle to a specific setting that corresponds to some
configuration. I just want to simply automate the switching so that
different configurations can be had at a touch of a button.

Ultimately it would be easier to use semiconductors but because this project
might end up commerial and because its use in audio and the market I'm
aiming for is very anal about solid state interfering with the quality that
I would like to do this with mechanical relays. Of course the smaller the
better for various reasons.

Jon

 

If you use a reed relay, put a small magnet
close to one end.
It will make the contact sticky, and a reverse
current will release the contact.
You might google for "latching reed relay"
I got 230 hits, the first one could be it.

 

Take a look at the Fujitsu FTR-B3G type parts, DPDT, in Mouser.
Drop-in equivalents are available from Omron and NEC. They switch very
fast (about a millisec) and seem very reliable.

We use the single-coil version (bipolar drive) and drive the coil from
a tiny-logic dual NOR gate.

John

 

Thanks guys. These are a bit larger than I was hoping for but might work.
I'll have to figure out something and might just go with fets, atleast for a
prototype.

Thanks,
Jon