Matador

Re: ELA M251 Inspired Microphone - Build Thread
« Reply #40 on: March 02, 2019, 01:30:21 PM »
I apologize for not updating the first post with schematics, etc.  I've finally ended my 10 year relationship with Eagle (and Autodesk's new ransomware) and have been transitioning my current projects over to KiCad.

I think I have a working schematic for the ELA M251 adaptation and I'll post it when it's ready.

EDIT: First page modified with link to new schematic.

« Last Edit: March 02, 2019, 04:13:53 PM by Matador »


Re: ELA M251 Inspired Microphone - Build Thread
« Reply #41 on: March 02, 2019, 09:59:34 PM »
That’s awesome as I have wanted to do this project for a while. And a BOM?

Matador

Re: ELA M251 Inspired Microphone - Build Thread
« Reply #42 on: March 03, 2019, 12:47:31 AM »
Working on it...

If you are impatient, the C12 bom in the other thread is mostly the same with the exception of a few parts

Re: ELA M251 Inspired Microphone - Build Thread
« Reply #43 on: March 03, 2019, 08:09:50 AM »
I've finally ended my 10 year relationship with Eagle (and Autodesk's new ransomware) and have been transitioning my current projects over to KiCad.
Ok I know wrong topic, but maybe a few words why Kicad over eagle ? Price ? 3d ?

Thanks

Gus

Re: ELA M251 Inspired Microphone - Build Thread
« Reply #44 on: March 03, 2019, 10:13:04 AM »
I would add a cardiod only switch.

Re: ELA M251 Inspired Microphone - Build Thread
« Reply #45 on: March 06, 2019, 04:06:06 PM »
In reference to my odd sound issues with a newly built ELA M251 hybrid. A bad 5000pf cap. Mic sounds great now in all patterns.  As Chunger says, yay humans win.

Matador

Re: ELA M251 Inspired Microphone - Build Thread
« Reply #46 on: March 06, 2019, 06:18:01 PM »
Were they polystyrene?  Those are always a pain due to heat and solvent susceptibility.

If people are looking for more robust options, I suggest either silver mica:

https://www.justradios.com/mica.html

Or NP0/C0G  MLCC ceramic capacitor:

https://www.mouser.com/ProductDetail/TDK/FA24NP02W472JNU06?qs=sGAEpiMZZMt3KoXD5rJ2NwPv70zxIRBTauMjI8hBH0Y0zBVMOKxMMg%3D%3D

Both of these types tolerate solvents and soldering much better.


Matador

Re: ELA M251 Inspired Microphone - Build Thread
« Reply #47 on: March 09, 2019, 04:50:29 PM »
Ok I know wrong topic, but maybe a few words why Kicad over eagle ? Price ? 3d ?
Price, yes, KiCad is open source and therefore 'free'.

I had purchased Eagle 4.3 back 10 years ago, and when Eagle transitioned past 5.0, they stopped supporting older installations, and then moved to a subscription-only model where they demand $15 a month to use the program that I already bought.

Re: ELA M251 Inspired Microphone - Build Thread
« Reply #48 on: February 29, 2020, 01:17:23 PM »
Hey everyone I just built this microphone a few weeks ago and have been needing some help I'm getting 120v from psu to the pcb, the heater has 6.3 on pcb and tube I had checked ground and everything is well grounded, checked the transformer plenty of times and all seems to be great all my resistors are reading correctly only ones I'm having an issue with are the styroflex 5000pf and 1000pf 100pf caps I get a reading from one of the 5000pf and 100pf but not the 1000pf and the other 5000 I'm trying to be as thorough as possible please help when you can

Re: ELA M251 Inspired Microphone - Build Thread
« Reply #49 on: February 29, 2020, 10:47:37 PM »
Anyone help me out please???


Re: ELA M251 Inspired Microphone - Build Thread
« Reply #50 on: March 26, 2020, 04:01:09 AM »
So I replaced the styroflex caps with silver mica and still no audio I rewired the t14 transformer and either way no audio I checked the ohms and they are correct I even wired them to direct output cap and ground points capsule is working fine I'm really not sure what the issue is could anyone help please? I'm getting 61v to the capsule c1 r17 r13 r12 polarity is good I'm also getting 124v and 6. 3v directly to the tube pin 5  someone please


 

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