Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TIMBO on January 28, 2023, 12:01:28 am

Title: DIY 1H Choke
Post by: TIMBO on January 28, 2023, 12:01:28 am

Hey guys, To start off these Fellars are hard to find or don't exist.
I know we use a choke in some amplifiers and too save a cost a resistor is used.
How hard would it be to do a DIY.
Plenty of stuff on the net for mH but a bit light on for the bigger stuff

Title: Re: DIY 1H Choke
Post by: PRR on January 28, 2023, 12:56:48 am

Why do you want 1H? B+ filtering, the exact value is not critical. Tone control, it has to be real close even with varying signal.

Title: Re: DIY 1H Choke
Post by: TIMBO on January 28, 2023, 03:25:44 am

Hey PRR, It came up here FUZZNIKATOR what is it??? (el34world.com) (https://el34world.com/Forum/index.php?topic=29838.0)
And why it was thought to be needed I don't know
The best I can find locally is the usual guitar amp ones and they start at 3Hs
The other sting is they start at around $50 plus postage

Title: Re: DIY 1H Choke
Post by: sluckey on January 28, 2023, 05:06:10 am

A 50mA choke would be overkill for that little amp. I'd just use a Hammond 194A (https://www.tubesandmore.com/products/choke-hammond-fender-deluxe-deluxe-reverb-etc). 4H@50mA. Less than $20.

Title: Re: DIY 1H Choke
Post by: TIMBO on January 28, 2023, 05:22:53 am

Local supplier is out of stock of those and it will still cost me $50

Title: Re: DIY 1H Choke
Post by: thetragichero on January 28, 2023, 09:03:25 am

how about mojotone? https://www.mojotone.com/Filter-Choke-for-6V6-Amps-125C3A

Title: Re: DIY 1H Choke
Post by: sluckey on January 28, 2023, 10:38:57 am

If you have some small single ended OTs you could use one as a choke. Just don't connect the secondary to anything.

Title: Re: DIY 1H Choke
Post by: kagliostro on January 28, 2023, 02:46:00 pm

Ciao TIMBO

use a gyrator and save money, space and weight

about Henries ... the more, the best

Here on the forum you can find schematics

the Merlin project specify that till 100mA there Is no need to use an heat sink

Franco

Title: Re: DIY 1H Choke
Post by: glass54 on January 28, 2023, 09:12:47 pm

Hi Timbo,
As Kagliostro (and PRR) have pointed out, Do you really need an Inductor in such a low current application.
I built a Preamp+Low Power test bed, using a 3 stage RC PS filter (1k 5W an 100u 450V). Works really well, so far max load about 40mA.
You could split your 220R 1W into 2x 100R 1W and add another 100R 1W instead of Inductor. (Use 100uF 450 for first 2 caps).
For the sake of our USA/European colleagues, component prices aren't too bad BUT freight to Australia is hideous!! Esp from the US in the last 3 years.
My thoughts Timbo, to get you out of the rabbit hole. :laugh:
Kind regards
Mirek

Title: Re: DIY 1H Choke
Post by: TIMBO on February 11, 2023, 09:29:57 pm

Hey guys, One of the local blokes has come through with the goods.
Power transformer to choke Doable - Page 2 (aggh.net) (https://www.aggh.net/discussion/index.php?topic=54173.15)

Title: Re: DIY 1H Choke
Post by: tubeswell on February 12, 2023, 06:14:41 am

Quote from: TIMBO on February 11, 2023, 09:29:57 pm

Hey guys, One of the local blokes has come through with the goods.
Power transformer to choke Doable - Page 2 (aggh.net) (https://www.aggh.net/discussion/index.php?topic=54173.15)

What a truly great friend Lindsay is to have!