GS 5 THRESHOLD PROBLEM

[daverave]

If thershold is connected between +12 and - rail or GND (I do not have your schematics) and your battery drop under 14V, regulator become noisy and your threshold also.

on the GS 5 there is an adjustment for fine adjustment of the threshold level which has a -5v & +5v on each end of the potentiometer...the -5v & +5v supplies are stable even with the supply voltage down to -10 volts...its the -10v & -14v supplies cha nge according to supply voltage...i would have thought the GS 5 should operate down to maybe 11 volts without any problems but im only guessing.

[Hyena]

If thershold is connected between +12 and - rail or GND (I do not have your schematics) and your battery drop under 14V, regulator become noisy and your threshold also.

[daverave]

Maybe there is a problem in the regulated line of +5 volts, which falls abruptly. This would explain why the threshold goes out of range.

ive tested the +5v & -5v supplies and are stable when the supply voltage is reduced....the - 14v & -10v supplies change according to lower voltage levels...i may try and increase the -10 v to -12v so if i drop the supply voltage a couple of volts then in theory if that is the problem the threshold should not change.....if not i may have to change the -12v regulator on the audio pcb to a low drop out type....like most of us we are still learning about detectors and cannot know everything that raises its ugly head.

[Jose]

Maybe there is a problem in the regulated line of +5 volts, which falls abruptly. This would explain why the threshold goes out of range.

[daverave]

basics electronics school again DR? again just bad student with low motivation to learn something.

Hi kt315....i cannot understand why people cannot be frank and say what the solution maybe...there are people on here with knowledge but unwilling to help...its only you and a few others who are interested in helping....its not a matter of school cause some electronic problems can be very vague and unencountered before.

[kt315]

basics electronics school again DR? again just bad student with low motivation to learn something.

[daverave]

were there problems with the GS 5 when battery voltage dropped to 13v and below ??? i see your point Altra with the - 12v regulator and the voltage does drop below - 12v when input voltage go's to 13 volts and below...i always thought these detectors should operate down to at lest 11 volts without threshold problems...im a little confused to say the lest

[kt315]

the circuit was designed for 14V
---
and what that designed for???? i use TWO 18650 in Elite. TWO IN PARALLEL. ie THERE IS JUST ONE SOURCE 3.6V.

[Altra]

Kt it is the small package T0-92 79L12. The easy fix is to use the right battery, the circuit was designed for 14V. Try 4x18650 Li ion(14.8v) or 12 nimh cells for (14.4V)

[kt315]

[kt315]

remember when you will change 7912 has un-standart pinouts.

[kt315]

https://www.ebay.com/itm/Mini-DC-DC-Boost-Buck-Module-3-2V-24V-to-5V-12V-15V-Negative-Power-Supply/323582086229?hash=item4b56fecc55:m:mlzhFLzZzbgkWqE7sllBMJQ:rk:2:pf:0

use

typical efficiency 82%. PERFECT!

[Altra]

i did some voltage tests on the audio pcb and noticed the -10v supplied by the lm 337 drops below -10v as the voltage drops below 13 volts input to the regulator...im not sure what the drop out voltage is for the lm 337 but surely it should still regulate even with maybe 2 volts above...maybe im barking up the wrong tree as to say.

The audio pcb has a -12v regulator (LM79L12). This could become unstable below -13v. There may be a modern version of this regulator that has a "low dropout" voltage?

[kt315]

it seems some people did read my trick of elite and do the same https://www.findmall.com/read.php?22...43#msg-2437843

[daverave]

linear stabilizer does not give 12V from 12V. must be some voltage reserve. 2V is minimal value. in Elite the one gives 10V output.
so 12V of battery will be very critical. ML holder are 10 pcs 1.3V Nicad gives 13V but if you put 8 pcs 1.2V nimh you get only 9.6V. you see - NOT 8, but 10 pcs.
that why you can not directly use nimh battery in Elite/gt using a holder for alkaline battery.

i did some voltage tests on the audio pcb and noticed the -10v supplied by the lm 337 drops below -10v as the voltage drops below 13 volts input to the regulator...im not sure what the drop out voltage is for the lm 337 but surely it should still regulate even with maybe 2 volts above...maybe im barking up the wrong tree as to say.