Fixed mode not so good

[Unregistered]

Hi Carl or anyone
Have built the Opt 2 HH, and seems to be working ok.
I am using a Minelab 10inch concentric mono and will see a 1gram nugget at approx 5 inch of which i feel is quite good in Auto track. Although when i switch it to Fix mode it will not even see it. In auto it will pick my gold ring at about 10 or more inches and I switch to Fix mode and goes down to maybe 4 or 5 inches.
I am using cmos for ic8 and cmos timer 555 for ic5.
any help.
tks
george

[Carl-NC]

What CMOS opamp are you using?

[Unregistered]

Found problem

Hi Carl
thanking you to reply.
I have found problem .. My soldering should be better.
george

[sisco]

HI

FOR IC5 MUST USE CMOS 555 LIKE 7555 OR TLC555 OR

NE555 IS OK ?

[sisco]

HI

please answer my question what is a better NE555 or 7555?

[Carl-NC]

I only have CMOS 555's. I believe the bipolar versions require a pull-up resistor on pin 3. However, Q1 and R5 effectively form a pull-up, so any 555 might work.

- Carl

[sisco]

Thank for answer CARL

for HH power supply i use 10*1.2 700mAh NiCa battry contacted serial

but after recharge out voltage between 13.5 to 15 volts.

can i use 7812 regulator for input supply of HH or this voltage(13 to 15)

not damage to my HH or unstable .

meanwhile i draw HH PCB with PROTEL for any have use.

[Carl-NC]

You should not need to use a 12v reg. The only potential issue is the 7660 charge pump chip... it is rated for 12v max but I believe I've run mine higher. You certainly don't want a reg feeding the coil.

- Carl

[sisco]

I use 7555 for IC5 but out voltage of IC4 = -2.3 and

IC4 very hot nearly burned.

so replace 7555 with NE555 then out voltage IC4 = -5 and work good.

thank

other question :what potentiometer must use onboard(one time adjust)

and what must use in front case.

[Carl-NC]

other question :what potentiometer must use onboard(one time adjust)

and what must use in front case.

That's entirely up to you. I would recommend putting pulse delay on the panel.

- Carl