GS 5 THRESHOLD PROBLEM

[daverave]

i decided to make a separate -10v circuit which has a drop out voltage of about 500 mV to try and correct the threshold drift when the supply voltage drops below 13 volts...but alas it has not cured the problem so i guess the when the supply votage dips below the 13 volts then it must affect more than the -10v on the audio pcb.

[ivconic]

Ah yes! One good hint for you Eric!
Remove the trimmer and put small SMD resistor instead.
You'll notice significant difference if you monitor the output on scope.

[ivconic]

Here is the picture promised in post 78.

[ATTACH]44714[/ATTACH]

The MC3608 converter sits in a PVC box to isolate it from the metal screening box. The added 4.7uF ceramic capacitors (blue) are across the input and output. Also inside the screening box is the linear regulator to give the -12V rail for the TX etc. This regulator is also fitted with similar ceramic capacitors. The TX/RX board sits under the larger metal plate which is connected to the ground on the coil connector, which is out of sight on the right hand end of the outer box. In this instance the battery supply consists of 6 x 1.2V rechargeable NiMh AA cells. Two 3.7V Li-ion cells would also suit, although NiMh were preferred as they are less likely to fail if the unit is inadvertently left on.
As mentioned previously, a -15V linear regulator could be used and the converter output set to -18V by means of the on-board preset. The screening box is RS part no.627-6304.

Eric.

I've been using such dc-dc step up converters for quite a while. Mostly with success. To supply various battery operated audio&music equipment. At few detector models too.
Additional filtering is mandatory, of course. Sometimes i add choke in series too.
I experienced huge problems only once, trying to supply 2.5GHz audio TX. There was a constant "whistle" in the background, completely spoiling the output.
No matter what i tried; i couldn't get rid of the whistle. With more complex filters i achieved only to lower the level of the whistle. But it was there all the time.
At the end i gave up and redesigned the circuitry.
As for the use at PI detectors; i haven't experienced any troubles so far. Even simple filtering like that will do the job just fine.

[kt315]

thank you Eric. you show all i wrote from start in this thread. now he will think WHO IS RIGHT.
low drop low drop low drop bla bla.

[Ferric Toes]

Here is the picture promised in post 78.



The MC3608 converter sits in a PVC box to isolate it from the metal screening box. The added 4.7uF ceramic capacitors (blue) are across the input and output. Also inside the screening box is the linear regulator to give the -12V rail for the TX etc. This regulator is also fitted with similar ceramic capacitors. The TX/RX board sits under the larger metal plate which is connected to the ground on the coil connector, which is out of sight on the right hand end of the outer box. In this instance the battery supply consists of 6 x 1.2V rechargeable NiMh AA cells. Two 3.7V Li-ion cells would also suit, although NiMh were preferred as they are less likely to fail if the unit is inadvertently left on.
As mentioned previously, a -15V linear regulator could be used and the converter output set to -18V by means of the on-board preset. The screening box is RS part no.627-6304.

Eric.

[dbanner]

Now to do some actual testing to see what the cut out voltages are on this particular one. Well, I learn something more everyday. I like tearing things apart to see what little treasures can be found.

[waltr]

Well I found out what my 8 pin chip was on my single Lithium battery PCM, it is a dual n-channel MOSFET.

That makes sense.The other chip is then the Voltage comparator and gate driver.

[dbanner]

Well I found out what my 8 pin chip was on my single Lithium battery PCM, it is a dual n-channel MOSFET.
This together with a battery protection IC is all there is.
Two important parameters in battery ICs are overvoltage threshold and undervoltage threshold. These numbers are the voltage levels at their limit; the IC will cut the cell out of circuit if the cell is being overcharged or over-discharged. These values are typically designed into battery protection ICs. These ICs come in a variety of threshold mixes,
Here is the circuit below. The same as the little board I pulled out of old phone battery.

[dbanner]

Edited

[Hyena]

i say again I DO NOT NEED protection board -!!! i get 12V from 3.7V and NO THAT PROTECT.

I do not offer you any. Congratulation to that
I just have this experience and often read "It might not protect". This one does. Thats basicaly all, no need to get upset

[kt315]

I use this module https://www.ebay.com/itm/Protection-...-/323202856662

The board is protecting your batteries! If any one of 3 cells get under 3V, it disconnect Vout immediatelly! I was surprised, why my machine stoped working, when it happened for the first time

I tried to find out if is possible to change this value to 3,5V but it seems that it is internaly set :-/

And surprise was also... You need to apply 12V to Vout to turn it on for the first time, otherwiase it looks like its dead. Then it produce Vout until you over-discharge it.

i say again I DO NOT NEED protection board -!!! i get 12V from 3.7V and NO THAT PROTECT.

[dbanner]

I figured out the 6 pin IC is single battery voltage protection IC like the DW01-P. The other chip could be a micro? The little circuit board also monitors battery temperature as well.(referring to little pcb I pulled out of mobile phone battery. It is definitely battery protection circuitry (PCM)

[Hyena]

I use this module https://www.ebay.com/itm/Protection-...-/323202856662

The board is protecting your batteries! If any one of 3 cells get under 3V, it disconnect Vout immediatelly! I was surprised, why my machine stoped working, when it happened for the first time

I tried to find out if is possible to change this value to 3,5V but it seems that it is internaly set :-/

And surprise was also... You need to apply 12V to Vout to turn it on for the first time, otherwiase it looks like its dead. Then it produce Vout until you over-discharge it.

[Ferric Toes]

Mr. Foster, my comments were never intended for you or anyone on this particular thread, I want to be clear about that.
So please dispel any notion that I was making any reference to you. I have only the highest respect for you.
For clarity, I am referring to another thread which someone posted a pic of gs5 main pcb top side, but when asked if he could put pic of bottom side, went into convenient silence. As I recall, he claimed to have the main board on the workbench from which he took a hi res pic of top side. But somehow could not put pic of bottom side. Ha.

Thank you for your quick explanation which is fully accepted.

Eric.

[dbanner]

I must respectfully disagree that the chip marked 2158 is a step down converter. It does not make any sense to use that chip.
I am sure that the chip is a Voltage comparator and MOSFET switch specifically designed for Li-ion protection. There is a huge market for such a chip, millions of Li-ion batteries, so a chip with the needed functions would be designed and produced.

Here is the typical ciruit used:
https://www.digikey.com/en/maker/blo...ell-protection

Are there any other parts, chips on that protection board?
Can you please post a good photo of this protection board?

Yes, yes, I fully agree. I jumped the gun on this one. From datasheet it doesn't make sense. Maybe isn't for protection at all. I not sure what it's function is or even if its the same chip. My camera on phone is not good enough for tiny chip. It says 2158 on the chip and is 8 legs as in datasheet I posted. There is also other 6 leg chip(3 on each side) marked 5231C. I think is small resistor array. I will investigate further.