Relay Attenuator w/o a DAC - which GPIO extender and case?

Help and Support Help
1

I want to use my Relay Attenuator with my preamp, not with a DAC - that means I must use a GPIO extender/spacer to lift the board so it will clear the USB and Ethernet connectors. Are there different heights of spacers? If so, what do I need?

After I add the spacer, which cases will provide enough height for the relay attenuator? Will a HighPi work?

2

Hi,
see e.g. berrybase.de/raspberry-pi-c … 223-e-m2-5

or conrad electronics or aliexpress or…

with kind regards
Tilmann

3

Thank you, but those are mechanical spacers, not GPIO extenders.

4

Sorry that I didn’t get your question.
Probably with a second stacking header you will get more space

rover.ebay.com/rover/0/0/0?mpre … 1497968752

If this answer is stupid again, please show me an image of your attenuator (connector)

Kind regards
T

5

That is exactly the right extender - but there are no dimensions on it. If I add it to my Pi, how much height will it add to the relay attenuator? The HighPi case might hold the Pi plus extender plus attenuator - or the stack might be a few mm to tall to fit in the case.

I would like to order everything I need in one go, so if someone knows how many mm the extender will add, I can measure and see. Or, if someone is using the relay attenuator without a DAC and can tell me what case they are using, then I can order that case knowing that it will work.

6

Hi,
the minimum hight is additional 11mm of the plastic body, but with 12mm spacers that should fit. Maybe you have to shorten the pins. DIY is sometimes trial and error…
Kind regards
T

7

The Adafruit 2223 GPIO extender is the shortest one I could find; it adds 2.5 mm for the body plus 10 mm for the pins. The relay attenuator has some components on the bottom side that interfere with the GPIO pins; I had to cut several of the pins on both sides of the relay attenuator’s connector.

Once the pins were cut and the RA was mounted, I needed 24 mm standoffs to fasten the RA to the Pi. This means that the Pi case must have about 38 mm of height above the Pi PCB in order for the lid to clear the top of the RA. A HighPi case won’t work, but a ModMyPi modular case with two expanders will.

I much prefer the HighPi case because the Pi PCB snaps firmly into place with a plastic clip, leaving the four mounting holes free for fastening the standoffs. The ModMyPi case expects you to screw the Pi PCB to the bottom of the case through the four mounting holes, leaving no way to fasten the RA (or any other hat). What is the point of having an extra-tall case if you can’t fasten the hat?

I will drill out the ModMyPi mounting holes to 3 mm and all the way through the bottom; then I can put the 24 mm standoffs on the RA (male end of the standoffs UP, and a nut on top of the RA PCB). This leaves the female side of the standoffs on top of the Pi PCB; I can put a 2.5 mm x 10 mm screw through the bottom of the case, up through the Pi PCB, and screw it into the female side of the standoffs. Then I will have to put small rubber feet on the bottom of the case to lift the screws off the ground.