Hi. I just registered and this is my first post. Here's the situation:
I bought these strange Shure teleconferencing (STM30W) mics off ebay. Strange thing about them is that--supposedly--they take 18 volts to power them. The guy who sold them to me sent along two 9volt batteries wired in series to do so. FWIW, I have no other info on these mics and Shure hasn't written me back with my request for the info so I'm kinda shooting in the dark here.
Anyway, I hooked them up and used them for a few days before the power ran out (I accidentally left them plugged in.....I know, I know....).
So, what I'd like to do is to power them using the phantom power of my Soundcraft 200. As I'm sure you know, phantom power is supplied on pins 2 and 3 of an xlr plug and gives 48 volts.
Now, the strange thing about these mics is that--from what I can tell (i.e. looking at how the mics are wired to the xlr pins)--these mics were getting their 18 volts on pin 3. In other words, pin 3 was getting the "+" connection to the 9volt "brick" and the pin 1 was getting the "-" connection to the 9volt "brick".
What I'd like to do is to build a little adaptor like this:
https://home.comcast.net/~elmastero/48Vto18Vadaptor.jpg
So, here's what I need to know:
Is there any way I could stepdown the 48v on pin 3 to 18v? Maybe a zener or something?
Also, could I step down the 48v on pin 2 to 0v?
Perhaps I'm just plain confused? Thanks for your time, all.
I bought these strange Shure teleconferencing (STM30W) mics off ebay. Strange thing about them is that--supposedly--they take 18 volts to power them. The guy who sold them to me sent along two 9volt batteries wired in series to do so. FWIW, I have no other info on these mics and Shure hasn't written me back with my request for the info so I'm kinda shooting in the dark here.
Anyway, I hooked them up and used them for a few days before the power ran out (I accidentally left them plugged in.....I know, I know....).
So, what I'd like to do is to power them using the phantom power of my Soundcraft 200. As I'm sure you know, phantom power is supplied on pins 2 and 3 of an xlr plug and gives 48 volts.
Now, the strange thing about these mics is that--from what I can tell (i.e. looking at how the mics are wired to the xlr pins)--these mics were getting their 18 volts on pin 3. In other words, pin 3 was getting the "+" connection to the 9volt "brick" and the pin 1 was getting the "-" connection to the 9volt "brick".
What I'd like to do is to build a little adaptor like this:
https://home.comcast.net/~elmastero/48Vto18Vadaptor.jpg
So, here's what I need to know:
Is there any way I could stepdown the 48v on pin 3 to 18v? Maybe a zener or something?
Also, could I step down the 48v on pin 2 to 0v?
Perhaps I'm just plain confused? Thanks for your time, all.