Archive for the ‘T&T’ Category.

Electric ingiter for model rockets

Keep in mind that my device does NOT comply with any safety standards whatsoever and safety is based only on common sense. It should not be used for anything else but model rocket hobby.


I started of with a simple schematics as shown below. The idea was simple – to heat a thin wire with huge electrical current as quickly as possible. I used N-channel MOSFET with drain current rated at 80 A. Power source is 4S 5Ah LiPo battery rated at 20C which means that it’s capable of delivering 100A constantly.



Schematics of igniter

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Raspberry Pi “folded” USB connector

The R.Pi is excellent module for many applications. Unfortunately it is not easy to stack USB modules connected to it. When USB module, e.g. RTL-SDR is attached to the R.Pi, the whole package become very long requiring larger box. One solution is to use USB extension cable, but it again require additional space. Here is another, more compact solution:

  1. remove the USB connector from your module
  2. place SIL header at the pins for USB connector
  3. connect the USB module back “folded around the corner”

usbvinkel1 usbvinkel2 usbvinkel3

Simple 5 minutes housing for Raspberry Pi with Camera

I took old cover from plastic sewer pipe (it was never used ha ha). Then I drilled four holes for M3 screws and one bigger hole for camera module lens. The housing was prepared from one litre PET bottle. I cut the bottle to proper size and inserted raspberry Pi with the camera inside the bottle. Next the LAN cable with passive 5V “PoE” was inserted.

Finally, I heated the bottle with hot air gun at the camera side to shrink a little bit and tightly close the gap between the plastic camera “holder” and the bottle .

Photos below will tell more than thousand words:

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How to program blank STM32F1 with STLINK V2 firmware

Today I found out how to “flash” blank STM32F103xC to make STLINK V2 debugger interface.

So, instead of desoldering from Discovery board to make miniture STLINK debug interface:

a09 - stlink v2 brain desoldered                  a0a - stlink v2 finally assembled usb mini dongle

it’s possible to solder blank (or any) STM32F10x with USB and at least 64k flash + 20k RAM, program it with STLINK V2 Firmware and use your new USB dongle for debugging STM32 or STM8 devices.

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Comparing two DIY PCB prototyping processes

Following this interesting heat-less, laminator-free process I decided to test it myself:

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Garmin VIRB video cable teardown

Here’s teardown of a Garmin Virb camera AV cable. You can find pinout and “ID” resistor at the end of the post:


virb usb

How to weld a thermocouple using two pencils

Power supply: 30V, 10A

How to make logo from DXF in Altium

This is simple tutorial, hot to prepare your favorite logotype in altium designer, either as overlay mask or in copper.

Step 1 – Draw your logotype. Prepare it as outline and save it in DXF or DWG version 11 or 12. Altium designer is very picky about that.


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QR Code in solidworks

I was looking for easy way to get QR code in 3D model within solidworks. Here’s one recipe hot to do it.

test  qr3dqrfinal

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