HHI rev C thru-hole boards available now !!

[silverdog]

Goldenkiwi

Nice job, a very neat construction

I too had problems adjusting R18, although I think initially I had missed a jumper, however after triple checking everthing I found that my 25 turn cermet was much more sensitive than I was expecting, eventually after many turns my voltage at TP4 dropped from 1.67v to -1v in less than 1 turn - very sensitive

My threshold also appeared not to work but I silenced my speaker by adjusting R46 (pulse width) - although not adjusted any further yet as I have no scope and my coil is just a basic test one, it is working ! I amazed myself !!

good luck and report back

[GoldenKiwi]

Hi silverdog, many thanks for your comment, and your suggestion.

I'll double-check i'm hitting the extremes of the pot ok, and then try changing the fixed values a little to give me a bit more range if required. I assume that would be appropriate to try.

My enclosure has arrived too, so ill be able to shield it better.

I'll report back!

Cheers
GK

[GoldenKiwi]

This afternoon I checked which end of R18 pot was closest to nulling IC6 with the intention of varying R17 or R19.... then I noticed I had their values wrong! R17 and R19 were both 1M not 100k.
Silly me!

After swapping them out I was able to null and had full wide range using R18 as expected. I was then able to complete calibration using R23, followed by R18.

I was also running it on an 8ohm speaker and noticed Q11 getting extremely hot and smelly, so swapped to a small 50ohm speaker which keeps Q11 cool. I'll probably change to 32ohm+ headphones.

I still don't have threshold control as expected, even after a fiddle with pulse rates and widths (which did vary it a little, thanks for the suggestion). I still have a constant high-pitch threshold. I'll triple check the values in the audio section then finishing mounting in a shielded enclosure and test outside before making any component changes(eg R30/R32)

I've also purchased a used scope which should arrive this coming week, so I can setup the timing I want.

Cheers
GK

[silverdog]

swapping R17 and R19 for 1M instead of 100k is an easy mistake as they are double listed in the parts list under both values

[6666]

Hi Silver Dog
just wanted to say thanks for the boards arrived a few days ago
been meaning to get here and say thanks
Fine boards

[Qiaozhi]

As discussed in another thread I have organised a short run of HHI rev C thru-hole boads

Well they arrived this morning and look very nice !!

I only have 20 available and these will go on a first come first served basis

prices are

$12 US for a single board shipped worldwide
$20 US for a pair of boards shipped worldwide

PM me for payment details if interested

Hi SilverDog,

Please can you tell me where you had these boards manufactured?

[cardin1]

Newbie here, first post. I would love to have a couple of boards. I'm sending a PM now that I can.

[Kieron]

1st post. Id like to get a couple of these boards too if you still have any. Ill PM