XPR 5350 telemetry and external relay

[foxtrotdelta]

We have a customer who would like to remotely set off their Whelen mass notification system using two XPR 5350s. The Whelen E2010 encoder has extra inputs that can accomplish that using an external closure so no problem there. We can also initial a telemetry "send pulse command" from the transmitting radio using an external, N/O push button that the receiving radio accurately accepts and activates its "on pulse command" for 2000 ms.

The problem now is finding a suitable external relay that can be controlled using the 5V TTL signal. Believe it or not, in the past with XPR4350/4550s, we've been able to use 12V automotive relays as the signal active low could sink enough current. The 2.0 radios don't work the same way. I see there are numerous relay modules that are meant for Arduinos (and other microcontrollers) to be able to control external devices but I was wondering what others here have used for similar TRBO telemetry applications?

ETA: Forgot to mention, we can power 12V relays from the radio's power supply so I'm not even sure if the microcontroller type relay boards would even work for this application.

 

[syntrx]

Solid state relay?

SSRs that can switch 40A+ loads with 10mA "coil" current are readily available. Quite a bit less than the 60-150mA required by typical electromechanical automotive relays.

 

[foxtrotdelta]

Thanks, meant to update sooner. We looked into that but the VIO pins can only sink 1 mA of current so they didn't work either. We did however find a TTL-driven relay board that uses a transistor and some resistors to reliably trigger a small 12 V relay that can be powered by the radio's power supply. It works really well and seems simple enough but I'll admit my circuit building skills aren't quite there yet!

Here's what we used: TTL - 1 Ch Relay Board

 

[FMROB]

I use the ELK 924 sensitive relays and they work well. http://www.elkproducts.com/product-catalog/elk-924-sensitive-relay

 

[zap]

Somewhere I have a link to a two transistor circuit that can handle up to 10A but can trigger on 10A that was designed for the GMT900 trucks which didn't have an easily tapable RAPs circuit for internal electronics.

 

[com501]

The Elk 924 is the correct device for this application. If you need a relay with additional timing functions use the Elk 960.

 

[foxtrotdelta]

All good to know for future reference when another project like this comes up. TRBO support was woefully unhelpful.

 

[com501]

TRBO support was woefully unhelpful.

Were you really expecting anything different?

 

[foxtrotdelta]

Sadly, no. However, I thought it would have been a simple question but after multiple emails back and forth it became apparent I was asking something that was too difficult for them to comprehend.

 

[syntrx]

All good to know for future reference when another project like this comes up. TRBO support was woefully unhelpful.

This is basic stuff that should be in the product documentation. Unfortunately, it's not.