Small caps for AMZ bypass relay??

[jamiefbolton]

I've ordered a few bypass relays from AMZ and I'm about to populate the PCB. I was going to use regular poly film caps from smallbear, but I remembered I had some small yellowish caps that look like tantalum caps. If you look at the populated PCB over at AMZ you'll see some yellowish caps that look similar to tantalum caps. However, I do not see and marking on the caps in the picture and there are no marking on my caps either. I'm not sure if mine are tantalum. I got them a while back from futurlec on a grab bag special of film caps. Guess they aren't tantalum?

here is the link to the pic at AMZ http://www.muzique.com/schem/bypass.htm

Any ideas?

[R.G.]

  That's two of them now - at least that I know of. Here's another: http://www.jackdeville.com/clickless_switch.php. Remarkably, the pinouts of the boards are almost identical. A couple of the signals are out of order from one to the other.

From http://geofex.com/Article_Folders/footswitch_pancake/footswitch_pancake.htm on 1/11/02, eight and a half years ago:

A computer controlled pancake
Here's another way to do it - put a miniature latching relay and programmable microcontroller inside the pancake. To do this, you just use a thicker spacer which is almost entirely cut away inside so there's room for a miniature relay and some electronics. The NEC EB2 series is cheap and effective. The PIC 12C508 controller costs $1.50 for one, and $0.97 each if you buy 25 (and they make dynamite replacements for 555's!). This controller takes over the entire task of reading the tactile switch, keeping track of on/off state, managing an indicator LED, and flipping the set/reset pulses into the latching relay. The 508 itself pulls 1 ma of current - less than the LED! - so it's not going to drain your batteries all by itself. The relay sets and resets with a pulse of 30ma for 20 milliseconds when it changes, so that's not going to eat your batteries up either. The relay provides metal-to-metal true bypass, and the controller manages the care and feeding of the relay. Total cost? Probably under $5, and some labor.

This setup requires more detailed work on the spacer and top cover. The spacer has to be cut out to fit all the electronics, and the top cover has to have a "presser" and a chunk of foam rubber glued to it to press the tactile switch. Fortunately, this is not much more advanced work than making a generic pancake.

Those of you who read GEO will recognize that this is the "Latching Relay Bypass", but with the CMOS hex inverter chip replaced by the microcontroller. That would not ordinarily seem smart, but with an eight pin controller that only costs $0.50 to $0.75 more than the (bigger!) 16 pin CMOS chip, it gets really reasonable.

The schemo in the article shows how to hook up a dual-coil latcher to the uC. A single-coil latching relay requires flipping two pins in concert instead of only one at once.

It might be a challenging layout to put a surface mount eight pin uC between the pins of the latching relay. In fact, it would be interesting to put the uC, voltage regulator, and any caps or resistors UNDER the relay. I think it's possible. 

[jamiefbolton]

geeze. i'm a noob. those are multilayer ceramic. those should do fine eh?