DJI Phantom I GPS receiver (DJI 11-22 V2) repair attempt  

I have bought a sunken PH1 around a year ago, managed to get it fly, but it is not able to see the GPS signal properly.

I have hooked up the board to my saleae and I have wrapped this tool to read the Saleae logic analyzer output CSV:

It turned out that it see some satellites, but the link quality is very poor: CNO (Carrier to Noise ratio) was mostly 0 and sometimes 28-30.

So I have replaced the ublox receiver module (to an uBlox 6T), it see more satellites, with better CNo (27-33) but still no signal lock in the system.

I have ordered today a ANT1575-2540A from the TME and we will see.
There is a ALM-1912-BLKG in the antenna path, but I have not been able to source it yet. And my hopes to the antenna is pretty high :D.

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Tyco Mutator schematic 

Schematic diagrams for the Tyco Mutator RC car (gathered from the FCC site).

Back in the days when I was kid I would give a lot for these docs when my car broke down. (It is waiting since then for the BL conversion...)

Tyco Mutator TY-W1237 schematics

Tyco Mutator TY-W2310 schematics

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Power LED lamp repair 

My father bought a second hand high power lamp powered by 3 18650 cells.

Unfortunately after installing the batteries there were no way to turn it off.

I have opened up with: "worst case I will put a switch to it" in my mind.

The circuit inside is simple: basically an SOT-23-6 IC marked with 819L 48 a power P fet in SO8 package and some current limiting resistors:

After doing some google fu I ended up on this website:

It turned out that the IC is a Shenzhen Fuman Elec FM2819 The datasheet is only available in chinese, but pushing through the google translate did not helped either.

I have noticed one thing: there were an unpopulated 0603 place parallel with the pushbutton. The russian blog mentioned above that he have had found a cap in the box fallen from the same place. I have followed his advice put a 0603 100nF cap there and now the lamp works as expected.

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STLINK-V3SET teardown images 

Just received from mouser a brand new STLink V3.

Here cames a bit of teardown of it.

Powered by an STM32F723 BGA variant.

It has a pretty nice construction with insightful features (USB to CAN, I2C, SPI, JTAG, SVD, SWIM).

I would love to use this a general tool. (Patch AVRDude to flash AVRs with it, patch flashrom to flash random SPI flashes, etc.)

USB descriptors:


Shipped with the latest FW:

The MB1440B is a kind of passive shield, just some protection diodes and a SN74LVC2T45 level shifter present for the SWIM.
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strreplace for EAGLE ULP 

string strreplace(string original, string toReplace, string replaceWith){
string ret = "";
string left = original;
while (strstr(left, toReplace) >= 0) {
ret += strsub(left, 0, strstr(left, toReplace));
ret += replaceWith;
left = strsub(left, strstr(left, toReplace) + strlen(toReplace));
ret += left;
return ret;

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