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• Expansion chamber prototype

  M. Bindhammer • 07/24/2016 at 08:07 • 0 comments

  Here are some impressions of the prototype:

• Radioactive sources

  M. Bindhammer • 05/31/2016 at 17:00 • 0 comments

  1. Uraninite

  Try to buy Uraninite (formerly pitchblende) at a mineral show. I bought some pieces of Uraninite from the famous formerly Russian uranium mine of Hartenstein, Saxony, Germany, at an internet mineral show. Uraninite contains up to 88% uranium. Uranium is weakly radioactive because all its isotopes are unstable. Below video shows the radiation measurement with a GAMMA-SCOUT Geiger counter.

  2. 241-Am

  The most common Americium isotope ²⁴¹Am can be obtained from an ionization smoke alarm. The isotope has has a half-life of 432.2 years. ²⁴¹Am decays mainly via alpha decay, with a weak gamma ray product:
  

  Next figure shows a dismantled Ei100L smoke alarm. The red, round structure at the right is the ionization chamber.
  

  The washer shaped part in the middle of the lower electrode of the ionization chamber contains the ²⁴¹Am. It has an activity of 33kBq.

  Do not touch it directly! Always use tweezers or pliers. If alpha-emitting radionuclides do enter the body, alpha radiation is the most destructive form of ionizing radiation. A large enough dose can cause any or all of the symptoms of radiation poisoning.

  Trimmed ²⁴¹Am source soldered onto the brass disc described here. Make sure, the alpha particle emitting side points to the center of the brass disc.

  
  

• PCB design

  M. Bindhammer • 05/28/2016 at 13:28 • 0 comments

  First vision of the high voltage and laser power supply PCB:

  I didn't add ground planes due to the high voltage.

  Blank PCB:

  Populated PCB:

  BOM:

  QTY.	REF.	DESCRIBTION
  2	C1, C2	Electrolytic capacitor, 10μF, 63V, lead space 2.5mm
  1	C3	Ceramic capacitor, 1μF, 16V, ±10%, 0805
  1	C4	Electrolytic capacitor, 33μF, 63V, lead space 2.5mm
  1	C5	Ceramic capacitor, 10nF, 16V, ±10%, 0805
  1	C6	Ceramic capacitor, 100nF, 16V, ±10%, 0805
  1	C7	Ceramic capacitor, 10nF, 16V, ±10%, 0805
  5	C8, C9, C10, C11, C12	Ceramic capacitor, 100nF, 1000V, ±10%, 2220
  5	D1, D2, D3, D4, D5	SM4007, DO-213AB
  1	/	DC power jack, PJ-202A
  1	IC1	Timer NE 555 D SMD, SO-8
  2	/	PCB mount screw terminal, 2 pins, lead space 3.5mm
  2	/	PCB toggle switch, 5236AB, lead space 4.7mm
  1	Q1	N-FET BUZ71, TO-220
  1	R1	Resistor 12kΩ, 1%, 0.125W, 0805
  1	R2	Resistor 4.7kΩ, 1%, 0.125, 0805
  1	T1	PCB transformer, 6V/230V, 1VA
  1	U1	800mA low-dropout linear regulator LM1117MPX-5.0, SOT-223
  1	U2	1A low dropout regulator for 5V to 3.3V conversion LM3940IMP-3.3, SOT-223

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