SURF PI PROBLEM

[daverave]

my supply voltage is 16 volts but as i decrease the voltage i noticed the sample pulse is not tracking the back emf curve so the sample is in the wrong position the more the voltage drops and the detector looses depth...how can i correct this so both the curve and sample pulse keep in tracking ???

[kt315]

i open datasheet on tlc555... and see you use tlc555 on upper of nominal supply - Single-Supply Operation From 2 V to 15 V.
15V is maximum for it. you use it abnormal on the risk, on edge of crash.

loving crashtests?

[daverave]

i did some more testing....if i set the sample delay at 10 uS and the supply voltage at 16v which is ok...but if i reduce the supply down to say below 12 volts then the decay curve changes and then the sample is in wrong position like in a dead zone and then no response from detector if target waived in front of coil....if i change the sample delay to 15 uS then i can still detect a target at around 12 volts....maybe the only way is to double the voltage to 32 volts and use a 16 volt regulator to the power supply.

[daverave]

can someone please advise on this cause i need to solve this problem so i can reassemble my surf pi.

[golfnut]

u could try something like 18V lithium pack from cordless.

Put a low drop out reg in and run it at about 15V. Most liear regs drop around a volt or less now.

Old 7805 s used to be about 2.5V drop so needed 7.5 minimum in

[kt315]

12V voltage of batt goes on IRF and tlc555 generator directly. no there reg.

[daverave]

thanks kt and other guys for your help.