Which four Knobs for HH PI?

[douglas]

I am using an aluminum control box from a Radio Shack treasure finder BFO.
I spray painted it black with automotive paint.

It will support four pots and maybe one switch. I don't need a volume control


Which four should I choose?

I was thinking of:

1. Main delay with On/off

2. Threshold

3. Tx pulse width

4. Rx pulse width..

any sugestions?

[Kevco]

Hi Douglas,

Now that I have my HH working, and have a better feel for the variables than my beginning ignorance...... So take my suggestions with a grain of salt. Others I'm sure have much more experience. But from what I've seen so far, I would suggest:

On/Off Main Delay
TX pulse width
SW2 (autotrack on/ static mode)
--- Maybe for these two below? ---
Threshold (?*)
Secondary delay (?*)

(*) comments:
THRESHOLD:
If the unit is in Autotrack mode, the threshold stays fairly stable. Perhaps it could be moved to PCB pot instead? But if you use static mode, an occasional threshold adjustment seems common (I'm using a CMOS equiv for the TL072 - for longer sample & hold delay). The TL072 drifts in just 10-20 secs, as Carl mentioned in his paper, which is why I switched to CMOS.

RX PULSE WIDTH:
I learned from Carl, he mainly uses 20-25 uSec for RX PW. Although it improves sensitivity somewhat, it doesn't change things by much. That could probably afford to be PCB mounted.

SW2 - AUTOTRACK / STATIC Modes:
I use this a fair amount. Especially when zeroing in on targets, after the main signal was found. I am also using a small stupid old solenoid wound kynar wirewrapped coil, for pinpointing, which almost always is in static mode.

SECONDARY DELAY:
I have this panel mounted. But I don't move it much. I keep mine around 100-150 uSec delay, with minor differences.

VOLUME:
I mainly use headphones, and for those, I keep the volume all the way to minimum, which still is plenty loud. I have a headphone jack, with a speaker that is also switched. When I use the speaker, I do need more volume.

I have not messed with the frequency or sensitivity. Both are near the center of the pots' wiper range.

Kevco

[Kevco]

ON/FF switch.....

I used the common pot mounted switch (ganged with a pot). I combined my volume & on/off switch in one control. Just like the usual portable radio control. That saves extra space for a separate on/off switch.

Kevco

[douglas]

knobs.

This is definitally the way to go. Unfortunitally, I began working on the Surfmaster PI londboard as well I have gotten more imeiadte results with it as it is a n eaier circuit with fewer adjustments. I will apply what I have learned to the HHPI. The HHpi is built but I want to switch out some of the caps for higher tolerance ones. I also have learned how to choose a good value for damping reistor. I am waiting for my coil parts to show up, and I have to finish the SMPI completelly before I move on to the more complicated HHPI I will post some photos I promise.

I want to know what kind of depth is possible with the HH (in air) mine seems to need some work.