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i have a problem with a GS 5....once i adjust the threshold to correct level then ok...but once the battery voltage drops below 13 volts then the threshold go's a bit louder and also below 13 volts i cannot zero the threshold into silence...could anyone offer any advice on this problem.
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Link to EXACT Schematic you are using please? -
Eric lost hard disc crashed and all info on it. so we do not have detail voltage list in all test points and the schematic on GS5.
unperspective case.Comment
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Hello waltr....i have no link....its a GS 5 issue 2...maybe some other pulse detectors have similar problems.Originally posted by waltr View PostComment
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Hi kt315...i remember some years ago when i had a minelab elite the same problem would happen when the voltage level dropped to a certain level and the threshold would then go too loudOriginally posted by kt315 View Post
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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.Comment
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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.Originally posted by kt315 View PostComment
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it seems some people did read my trick of elite and do the same https://www.findmall.com/read.php?22...43#msg-2437843Comment
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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?Originally posted by daverave View PostComment
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remember when you will change 7912 has un-standart pinouts.
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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)Comment
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the circuit was designed for 14V
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and what that designed for???? i use TWO 18650 in Elite. TWO IN PARALLEL. ie THERE IS JUST ONE SOURCE 3.6V.Comment
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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
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