thor.zmt
Well-known member
This "datasheet" is a bad joke!![]()
I found somewhat more useful information:
![1716381287272.png 1716381287272.png](https://cdn.imagearchive.com/groupdiy/data/attachments/81/81158-eee1b88984d852dbdbe1d143b09eba6d.jpg)
![1716381363598.png 1716381363598.png](https://cdn.imagearchive.com/groupdiy/data/attachments/81/81159-5e7cf9c73a61621d5d46fbf9e0406df9.jpg)
So basically we can expect -2dB @ 20Hz & 20khz and 1.2V across the primary at 60Hz give ~1% THD, so 0.6V max. @ 30Hz. So in 10:1 mode maximum 30Hz output at 30Hz & 1% THD = 60mV.
Recommended load in 10:1 stepdown is 500R or higher.
Thomann has recently discontinued these transformers, the price was really good.
Banzai has it at 20 Euro
And I think it would be worthwhile for a first build, including for @Emmathom to make this SELA S12 Clone with the NTE10/3.
It would literally be a stereotypical early tube mike. My recommendation based on Sim's for a bit more tube current, and easy to build, using 12V/1A DC (plug top SMPS?) to power:
![1716386088003.png 1716386088003.png](https://cdn.imagearchive.com/groupdiy/data/attachments/81/81163-efc303d5e864564b931058e46e3f324f.jpg)
As HT supply either this DIY Kit or something build on Veroboard to the published circuit should work well:
https://threeneurons.wordpress.com/nixie-power-supply/hv-supply-kit/
The kit is available on e-Bay for 16 Bux, which beats a smack in the gob:
HV Power Supply - 12V In, 45 to 350V Out - 5.5W Nixie, Old Radio - US Seller
E.g. this, which can be made with all through hole parts:
![1716385801094.png 1716385801094.png](https://cdn.imagearchive.com/groupdiy/data/attachments/81/81161-197a638bb580953ddee0b7439ec34c96.jpg)
![1716387588145.png 1716387588145.png](https://cdn.imagearchive.com/groupdiy/data/attachments/81/81169-8d9ce60f13ed6fc18ba54a38a2b44b18.jpg)
With the suggested 90V HT the tube will draw around 3.5mA and total gain with the Transformer accounted for will be in the region of -3dB, so it's not a very "LOUD" microphone.
A bit of extra gain is to be had by replacing the 10K Anode load resistor with E352 (3.5mA/100V) Current Regulator Diode, e.g.:
Mouser - Semitec E-352 Current Regulator Diode (currently outstock preorder)
![1716387060007.png 1716387060007.png](https://cdn.imagearchive.com/groupdiy/data/attachments/81/81167-1456b44a930a0c768f91f5ab2d239b02.jpg)
I think together with being able to use a basic 12V SMPS as overall power (or even a USB-C battery pack with a USB-C PD trigger PCB set for 12V), the small DC-DC boost converter a very easy DIY project emerges with both an option for a transformer less and transformer based option, that is a very realistic proposition.
Attached is also the .tsc file (as zip archive) that was used in the simulation - just download free Tina-TI and open the TSC file....
Thor
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