replace 9v with 18650 Lion - bounty hunter discovery

[kt315]

balansir from Eddy http://smartelectronix.biz/publ/pros...orov/1-1-0-101

[Funfinder]

The USB-Plug Of Death !


It comes with 11v and when I would stick it into a computers USB-out
it kills the internal circuits! Which one of you guys I should visit?

USB-pins: ground - 3,7 - 7,4 - 11,1 volts (normal USB = 5v @ red-black cables)

And the special adapter-cable is for the modified Blisstool LTC detector so
the driller-battery can be used as reserve even with balance charging.

Thats real useful hardware-hacking, created already 3 years ago!

[kt315]

this converter STEP-UP, new typo, was bought and i hope to insert it in BH. power will be one 18650. i take them from trash notebook batts holder.
also you can use any li-ion from smartphone.

[kt315]

got it. smallest pcb... gives symmetrical voltages... nice.

[Skippy]

There is also another similar type of board from China, it uses the DD1718PA chip. Many choices of output voltage, including +/-9 Volt.:
Ebay example listing:
https://www.ebay.co.uk/itm/195734432266
Studying the PCB of a +/-15V version, it is easy to see the two resistors that form a divider network, setting the output level.
The divider is 22k6 to +15V, and 2k0 to ground. The junction of the two resistors gives voltage = 1.23V when output voltage is 15V.
This gives you the option of changing the output to +/- 10V and putting on LDO linear regulators for a cleaner supply. Or buying a 15V version and converting it to 9V if there is limited stock from the sellers.

[Skippy]

I should add: that DD1718 module is technically a +9V boost regulator, but with an added charge pump ( hence two extra schottly diodes and two caps) to create the negative rail. As a result, it's voltage is slightly less than the positive, has lower output current capability, and is not so well regulated.
It looks like the one KT links to has regulation on both rails?

[kt315]

thank you Skippy... my board gives +-8.93..8.96 V but checking with small loading, 510 Ohm on every output... the voltages are fixed. must check in BH with full load
https://www.aliexpress.com/item/1005005782269673.html

[Altra]

I bought a few of those a while back. They would rapidly burn out under light load. So I looked around to see what was going on. Comparing the Chinese schematic to some app notes. I found the Chinese modules were missing a current limiting series resistor on the negative charge pump.

I added a 4.7 ohm and the modules seems to work without blowing.

In this article they call it "R-CHG"

https://www.analog.com/en/design-not...t-voltage.html

In this app. the resistor is "R6" in figure 5.

https://pdfserv.stg-maximintegrated..../an/AN3740.pdf