B&K microphone power supply - help needed - Page 7 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 9th January 2017, 06:04 PM   #61
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Blog Entries: 4
Use this to charge the lipo battery: 3.7V Lipo Battery USB Charger Cable for Syma X5 X5C Hubsan H107L H107C RC Drone | eBay

Its weird that the charger and a power supply cost less than some perfboard to build the rest.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 9th January 2017, 10:28 PM   #62
diyAudio Member
 
Join Date: Dec 2005
Location: Netherlands
Hello,

Thanks for those links, pretty astonishing what those units cost, delivered to our door & all.

Most useful here would a simple interface box that starts from +48V Phantom Power (XLR-3), some back of envelope drawings show that this should be well possible.

Haven't found the opportunity to check if the B&K unit actually still works, the lab supply, R & C should answer that.

When that's on the table, having a few boxes with each different powering-options (battery as well as P+48V) sure wouldn't hurt.

Best regards
  Reply With Quote
Old 10th January 2017, 04:38 AM   #63
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Blog Entries: 4
48V Phantom power should work fine however you will need to figure out an inversion for the -in. You can cheat and use it single ended which would work fine but TOO simple.

4 mA is no power. Basically why you can't get the 200V bias or the heater with that interface.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 11th January 2017, 02:48 AM   #64
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi Demian,
The only problems with the Phantom power is that some are noisy. I can't remember the boards, but we had to redesign the phantom power supply completely. The other issue is that often the phantom power is less than the specified 48 VDC. I'd use a meter to confirm just what voltage you have to begin with.

Just a note to make people aware that you can't assume the phantom power is what the oft-quoted spec is. It was a rude surprise for us. No, these boards were not defective, they were designed that way. Possibly could have been Soundcraft, but don't quote me on that.

-Chris
__________________
"Just because you can, doesn't mean you should" my Wife
  Reply With Quote
Old 11th January 2017, 05:26 AM   #65
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by 1audio View Post
A battery powered version would make a lot of sense. It would not be hard. I would use a cheap DC-DC converter from China + a Lipo battery. Then probably a depletion mode mosfet plus a selected current diode for the current supply. Supply current does have an effect on the output voltage. With the B&K mikes they don't need gain so much less effect on the output. The output is high enough that you can use a follower inside and get a low output Z.

LM2587 DC-DC Boost Converter 3V-30V Step up to 4-35V Power Supply Module MAX 5A | eBay

I could sketch out the rest later if you want.
Actually if you want to detail the design I would be interested.
  Reply With Quote
Old 12th January 2017, 08:12 PM   #66
diyAudio Member
 
Join Date: Dec 2005
Location: Netherlands
Quote:
Originally Posted by 1audio View Post
48V Phantom power should work fine however you will need to figure out an inversion for the -in. You can cheat and use it single ended which would work fine but TOO simple.
I figure single ended would be fine indeed.

Just curious how you meant too simple ?
As in: too easy to solve this question to come up with a circuit between the P+48V & the 4mA resulting at some 12V at the BNC connector of the 2671?

Quote:
4 mA is no power. Basically why you can't get the 200V bias or the heater with that interface.
Yes, the 4155 capsule is prepolarized and I guess the 2671 has little more inside than a FET or a FET and a BJT. (Curious if a schematic will ever pop up, I don't see an easy way of opening the 2671, so rather not risk damagaging the unit)

Regards
  Reply With Quote
Old 12th January 2017, 08:21 PM   #67
diyAudio Member
 
Join Date: Dec 2005
Location: Netherlands
Quote:
Originally Posted by anatech View Post
The other issue is that often the phantom power is less than the specified 48 VDC.
Thought the standard (IEC 61938) allowed for 44 ... 52 V, so @ 44V the 4 mA should still be possible to deliver for the interface circuit (although B&K's own battery-box itself seems to lower the current to slightly over 3 mA as well).

Or are you meaning those 'phantom powered mic inputs' (seen them from Roland & Peavey, to mention a few) that happily go for 12V DC ?

Regards
  Reply With Quote
Old 12th January 2017, 08:26 PM   #68
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi clintrubber,
Yes. The ones that caused us trouble were sitting about 28 VDC, but with a lot of line noise on them.

At 12 volts, I'm calling the manufacturer delinquent. Even op amps run at higher levels in your average mixer.

-Chris
__________________
"Just because you can, doesn't mean you should" my Wife
  Reply With Quote
Old 13th January 2017, 12:45 AM   #69
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Blog Entries: 4
I'm fiddling with several variants for this. Single ended with a fixed supply may give the best results. Its want I was thinking originally. Phantom power is more of a PITA. If you ignore the -in and shunt it with a cap to ground and add a Zener to protect the mike from 48V its also simple (1 Zener would make it fit in a cable). Originally phantom power was intended for transformer coupled circuits but that seems silly for this application today. I have something working in sim for phantom but I'm not happy with it yet. It would be easier if the - from the microphone weren't also the shield/ground. And a good solution is dependent on the implementation of the supply circuit.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 13th January 2017, 02:01 AM   #70
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi Demian,
That's the best way to avoid the perils of various ideas of what "phantom power" is, and less customer complaints.

-Chris
__________________
"Just because you can, doesn't mean you should" my Wife
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
SLA batteries as power supply. What's needed? DavidJE Power Supplies 0 24th March 2009 12:13 PM
Power supply choke help needed audiobliss Tubes / Valves 4 1st August 2008 03:22 PM
dc power supply help needed skullkeeper Parts 12 12th May 2008 11:49 PM
Microphone power supply carlmart Power Supplies 3 28th February 2007 09:34 PM
Turntable Power Supply DIY needed promitheus Analogue Source 14 21st August 2006 12:02 PM


New To Site? Need Help?

All times are GMT. The time now is 04:31 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki