Hello!
Standard sealed relays can work fine I am sure. In the main application I use them in we only need a single normally open pole - for switching the output side of the TVC or Autoformer. Size is an issue as well, despite what you may hear. I selected the Coto based on the following criteria:
1- They can be driven directly from the microcontroller - saving the space of driving circuits and keeping overall system power consumption low.
2- They are small - not the smallest relay on earth but small enough to put them in the circuit where they should go and keep traces nice and short.
3- They are quiet. Not a big deal but a nice feature compared to some loud relays I have lived with in the past.
4- VERY Long life. These are rated for billions - not millions - of operations. Some OEM's I do designs for really got excited about that.
Sonic testing: I wired 5 relays in series and compared on my blind switcher to a straight wire. I could not guess which was which so on that front I figured I was done. I supose I could have compared others but really could not see the point. There are a lot of things to compare all the time so I don't go looking for others!
There are 2 downsides:
1- They are expensive. In singles they are about $7 each - compared to many 2 pole relays that might be 1/2 that price and offer the equivilent of 2 cotos (ie. about 1/4 the cost per pole). To get the cost down I have bought about 15000 of them so far. Qty 5000 gets the landed cost down to about $2.50 per unit - that is the sweet spot. After that qty the price does not drop much. The TAP had about 120 relays in it (input switching and all the level switching, etc) so the cost does add up!
2- The coto's became 'unobtanium' just after I started using them. Thankfully a UK oem using the same relays (Anatek Acoustics) pointed me to the Pickering equivalent. Turns out Pickering are the ones who made them first and coto cloned them. Pickering have a great name but are pretty much OEM suppliers (manufactued to order) so you need to but in qty to get their stuff.
Hope that answers your question. I know you'll see threads arguing for one type of relay/switch or another. Most are based on theories about what should work best, etc.... Having lived with these for a few years now I am very happy with them. Please contact me privately if you'd like me to e-mail info about purchase, etc to you.
Thansk and Merry Christmas!
John
