Harrison Ford Filter Feeler

[skizotom]

I've got two channels wired up, powered, and ready to go. 

I'm seeing that the input pads are marked

 +       -
 o   o   o

So, (naturally?) I assume that the unmarked middle pad is ground ... but,  while testing the wiring on the inputs I'm noticing that the input pad marked negative (rightmost input pad, when looking from the top of the board) is tied to ground - and the middle input pad seems to be where the negative input is tied to the ICs.

Am I missing some basic Ohm's-Law-ish principle, or is the board mis-labeled?

I searched within the thread for "input ground" and "negative ground" but didn't turn up any info.

So there doesn't actually seem to be a definitive answer to this question.  just a confirmation that they are marked wrongly. Are both input and output actually:
o o o
+ - G
?

 

[minor_glitch]

It's about time I finally finish this project (and 5 others collecting dust on the bench...). Haven't done any diy stuff for the last year.  I'm drawing a blank, so it's stupid question time!
Is 10VA enough for running 8 of these? I was looking at this guy: http://www.antekinc.com/an-0115/ but should I go for 25VA instead?

 

[dandeurloo]

Minor_Glitch I would go bigger to just be on the safe side of running 8 at once. 

 

[dandeurloo]

skizotom, Just the input pads have the wrong silk screen on them.  If you look at the bottom of the PCB or use your DMM you can see the ground pads are tied together. 

Correct wiring is:
INPUT        OUTPUT
+  -    G        G  +    -
o  o  o        o  o  o

I've got two channels wired up, powered, and ready to go. 

I'm seeing that the input pads are marked

 +       -
 o   o   o

So, (naturally?) I assume that the unmarked middle pad is ground ... but,  while testing the wiring on the inputs I'm noticing that the input pad marked negative (rightmost input pad, when looking from the top of the board) is tied to ground - and the middle input pad seems to be where the negative input is tied to the ICs.

Am I missing some basic Ohm's-Law-ish principle, or is the board mis-labeled?

I searched within the thread for "input ground" and "negative ground" but didn't turn up any info.

I hope that helps.

 

[minor_glitch]

Minor_Glitch I would go bigger to just be on the safe side of running 8 at once.

Great, thanks!

 

[Rocinante]

Hey all,
I'm building these in 500 series (so am wiring the pots off board and have found a source for dual 50k reverse log pots but they aren't the conductive plastic, is that alright? 
Has anyone tried pots other than the Omegs?

Dylan

 

[12afael]

personal note  "add note about the in and out connector on the pcb in the next pcb"

sorry guys!  :-[

 

[G-Sun]

Hey all,
I'm building these in 500 series (so am wiring the pots off board and have found a source for dual 50k reverse log pots but they aren't the conductive plastic, is that alright? 
Has anyone tried pots other than the Omegs?

Dylan

Aml 47k works fine

 

[snaper]

Hi Guys,


Quick question, regarding the schemo.
If I would like to use this with line levels (in a diy summing mixer), can I just simply omit the INA and DRV ICs?

 

[12afael]

if your system is unbalanced yes. it is an exact copy of the harrison filter.  you should check your source and input impedance of the surrounding circuit to maintain the performance (low impedance source and high input impedance ~10k)

 

[kdramsey]

Completed 8 channel Harrison Ford Filter.  I am real happy with the way it turned out!

Has anyone else using Dan's case noticed that the .050 marking for the HPF appears to be wrong? Instead it is labeled .50 which would indicate 500Hz unless I am missing something...

 

[guilds100]

Does anyone have a good source for the ICs on the bom. I would like to build this unit but cant source all the chips.

 

[john12ax7]

Does anyone have a good source for the ICs on the bom. I would like to build this unit but cant source all the chips.

Mouser should have everything

 

[guilds100]

Does anyone have a good source for the ICs on the bom. I would like to build this unit but cant source all the chips.

Mouser should have everything

I checked mouser and they dont have the tl074p

 

[john12ax7]

It seems they don't have the DIP version anymore, but looks like Digikey does.

You could also substitute other good quad jfet opamps.

 

[Harpo]

http://www.mouser.de/ProductDetail/Texas-Instruments/TL074CN/?qs=sGAEpiMZZMtCHixnSjNA6NVXWo9AXLOeoUCxMTuUhxw%3d about 20000 stock ...

 

[G-Sun]

btw: I'm very glad I built 2ch of this.
Just comes so handy in the studio

 

[elskardio]

Hello,
Does anyone have a drilling template for the Harrison filters?
Thanks

 

[petermontg]

Any boards left??

 

[G-Sun]

Any boards left??

http://collectivecases.com/?product=harrison-ford-filter-pcb