Glad to help, Tony. I'll reply to the mailing list in case anyone else is interested.

First, your computer needs a port (usually serial) to trigger the relay. My computer did not have one, so I bought a USB > Serial cable.

There are discussions online regarding that the different types of USB > Serial cables do or don't work for this purpose. The following cable is working well for me:

https://smile.amazon.com/gp/product/B006AA04K0

(if you don't already have a charity linked to Amazon's "SMILE" program, now is a good opportunity to set that to AMSAT!)

As I mentioned earlier, to make it easier to access the serial pins you need, a breakout adapter is handy. Others may wish to solder a permanent connection, but I use the following:

https://smile.amazon.com/gp/product/B00WW6P636

... and to save people having to scroll through previous posts, here is the relay itself:

https://smile.amazon.com/gp/product/B00E0NTPP4 (please note that we'll only be using one of the two relays on that board)

And now to actually answer your question, I threw together an ugly image file that shows the physical wiring connections as well as the schematic so you can know what it's doing. I also included a screen print of where I have the PTT Com port selected in HS_Soundmodem. Of course the Com Port number will be different on everyone's computer and on top of that, you might be using something other than HS_Soundmodem to control your PTT from the computer. But in the following diagram, you can see how I'm setup for "Com15":

http://www.qsl.net/k/k4kdr//files/PTT-relay-wiring-plus-schematic.png

... hope that helps!

You also asked about drivers, etc., on a Windows machine. Other than allowing the USB > Serial cable to install whatever it needs to download to function, you'll be fine. The computer has no idea that the RTS signal on your serial port is controlling a relay. So, nothing is needed on the computer for the relay itself.

And as for the 5 VDC to power the relay coil, you could certainly use an AC adapter of some kind, but I just cut the end off of a short USB printer cable and used the red & black wires to give me a convenient 5 VDC from the computer (or in my case actually from a multi-port, powered USB hub).

-Scott, K4KDR

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-----Original Message----- From: Tony Sent: Sunday, October 22, 2017 2:11 PM To: Scott Subject: Re: [amsat-bb] Falconsat Success

Scott:

That's exactly what I'm looking for. The fact that it has isolation is a real plus. Could you pass along a few more details regarding the type of USB cable used and how you wired the relay to your PTT line on the rig?

I'm not much of a PC guy so every bit helps - never home-brewed a USB PTT.

Thanks Scott

Tony -K2MO

On 10/22/2017 9:39 AM, Scott wrote:

Congrats, Tony!

The following relay has been working very well for me to handle PTT:

https://www.amazon.com/gp/product/B00E0NTPP4/ref=oh_aui_detailpage_o01_s00?i...

... I use 5 VDC from a USB cable for the coil voltage with the application of that coil voltage being triggered by the serial RTS signal from HS_Soundmodem. The above relay is great for that since the coil circuit is controlled by an opto-isolator that can be operated by a low level signal like the serial RTS.

The following item sure made it easy to attach a pair of wires to serial RTS & ground:

https://www.amazon.com/gp/product/B00WW6P636/ref=oh_aui_detailpage_o04_s00?i...

-Scott, K4KDR

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On Sun, Oct 22, 2017 at 4:39 AM, Tony dxdx@optonline.net wrote:

...

All:

Managed to work Falconsat this morning using UZ7HO's Soundmodem, WISP and VSP. I don't have a PTT circuit so I had to use the rigs MOX function to send file requests. I wouldn't recommend doing that for obvious reasons -- need to build a PTT circuit ASAP.

If anyone is interested, this video guide shows the basics on how to setup Wisp and Soundmodem using HW-VSP. See: https://www.youtube.com/watch? v=1ahlA-bRb5A

73, Tony -K2MO