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Assembly Instructions

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Oliver Keller edited this page Aug 19, 2020 · 31 revisions

Table of Contents

Required Parts
Required Tools
Build Instrcutions
Troubleshooting

Required Parts

The DIY Particle Detector comes in two variants

Both variants require the same circuit board, but with different sets of electronic parts, the schematic drawing features both sets of parts in an overview.

Tips for ordering parts

Please use the two kitspace links above to find the right order codes for each variant from several different electronic part suppliers. There are no additional costs if you use its '1-click BOM' functionality, it merely copies the right amount of parts and their order codes into the respective shopping carts of supported suppliers. www.kitspace.org is community-run and intends to simplify the uptake and distribution of open hardware projects.

Unfortunately, not every electronic part supplier ships to private individuals in all countries. Mouser and Digikey are currently the more universal ones from the suppliers supported on kitspace. Both offer free shipping if a minimum threshold of ~50 USD/EUR is reached.

If you want to order as a private person, please check first which of the listed supplier supports this in your country. Then create your own account at the supplier's website, log in with your account and finally use one of the two kitspace project links (see above) to populate your shopping cart with the correct order codes for all required parts. Please create a GitHub issue if you have problems with certain parts.

Required Tools

Optional tools:

Build Instructions

Before you start soldering, make up your mind about how and where you want to mount the detector inside the metal case (please consider all the remarks on that page!).

If the enclosure is quite small, you may want to put the large capacitor C8 and/or the diodes D1-D4 on the opposite side as they are marked on the circuit board. For example, the detector is more sensitive if the diodes are very closely placed in front of a radiation window. C8 could be rather mounted on the opposite side of the board in such cases.

If the enclosure is rather large and radioactive objects will fit inside easily, the default position of all components on the board can be kept as marked.

Always use one of the two parts overview PDFs linked at the very top as an assembly guide. Solder the components as they are listed on those sheets, top-bottom, left column followed by the right column.
General note: The small capacitors and resistors can be mounted either way. Only C8, the diodes D1-D4 and U1 must be mounted exactly in the correct orientation since these are components with a specific polarity.

  1. solder the resistors in the correct places as marked on the board, carefully checking for their color bands
  2. cut all residual and protruding resistor leads away as close a possible to the board
  3. solder the small (yellow) capacitors in the correct places as marked on the board
    • C5 should be mounted as flat as possible if the selected enclosure is very small and if the battery will be directly on top of it
  4. cut the residual and protruding capacitor leads away as close a possible to the board
    • the leads of C5 must be cut as short as possible such that U1 can fit closely on top of them
  5. solder the large capacitor C8 on that side of the board that fits better to the available space in your enclosure
    • if unsure about the best position, keep 2-3 mm of free space between C8 and the board - this extra lead length provides an option to later bend C8 horizontally/flat if necessary
  6. solder the diodes, 4 x BPW34F or 1 x modified BPX61, respecting their polarity (anode vs. cathode)
    • the cathode pins must point to the board center, marked with the letter 'K' (see images below)
    • the BPW34F's cathode_pin is marked with a notch
    • the BPX61's anode_pin marked with a notch, which must point away from the board
  7. solder the amplifier chip U1, respecting its polarity: pin 1 is marked with a circle
    • double-check that the pins from C5 are cut short enough and do not touch each other
  8. check all solder points on the board for possible short circuits, cut them short/flat if required
    • optionally measure the resistance on the +/- 9 V battery connector holes, it must be much higher than 0 - several kilo Ohms
  9. make sure the chosen enclosure has all the required holes in the correct size for
    • signal output connector (BNC or audio), check if it fits in place and mount it
    • on/off switch, check if it fits in place and mount it
    • optionally a "radiation window"
  10. solder the black ground wired of the 9 V battery clip into hole labeled '-', next to '+9V' and C8
  11. solder the red wired of the 9 V battery clip to the middle pin of the on/off switch
  12. strip the insulation from 3 short pieces of electrical wire at the ends
  13. solder one short piece of electrical wire between the on/off switch and the hole labeled '+9V' on the board
  14. solder a pair of short pieces of electrical wire between the board and the signal output BNC connector
    • solder two wires into the holes marked with 'signal' and '-' on the board
    • solder the other end of the 'signal' wire to the BNC connector's inner pin
    • solder the other end of the '-' wire to the outer part of the BNC connector, usually surrounded by an extra connection ring Alternatively, the '-' wire can be soldered directly on tin box walls next to the connector (does not work with aluminum cases).
    • if an audio connector is used instead of the BNC connector, tip/sleeve should be connected respectively
  15. check all wire connections for possible short circuits, correct them if required
    • optionally measure the resistance on the +/- 9 V battery clip connector, it must be much higher than 0 - several kilo Ohms
  16. fix the circuit board in place with screws, either via the two metalized board edges or one of the 3 metalized holes
  17. connect the 9 V battery, place it inside the metal enclosure
  18. close the lid of the enclosure
    • light must not reach inside, even the tiniest holes and slits must be covered with sticky tape from the inside

Top sides of the electron-detector variant on the left, the alpha-spectrometer varaint on the right:
The central label 'K' between the diodes D1-D4 marks the position of the cathode pins.
('K' was derived from the Greek word 'kathodos' - it also looks like the electronic diode symbol)

Troubleshooting

If measuring does not work properly or you are not sure about it:

  • connect the detector to a software or a hardware oscilloscope (recommended)
  • the signal line on the screen must change briefly every time when you switch the detector on/off
    • if you see no reaction, check all the wire connections, solder joints, and that the battery has around 9 Volt
  • try to measure something that is proven to be considerably radioactive
    • a vintage piece of uranium glass or ceramics from the flew market that produces at least 1 count per second with a Geiger-Müller counter
    • a big bag of potassium salt (KCl, sold as "No-Salt", "Lo-Salt" or "sodium-free table salt" etc.)
  • put the object as close as possible in front of the diodes, if possible inside the metal case!
  • put a thick black piece of cloth or towel on top of the detector case to make sure that all light is blocked
    • consider a darker room and avoid bright sunlight during the first tests
  • do not touch the detector or the table during the measurement (important with tin candy boxes)
    • if you hit the detector hard and quick with a finger, the vibration should appear as a short sine-like wave
  • if you see continuous 50 Hz, 100 Hz or much higher frequency sine waves:
    • most likely some fluorescent neon-tube or LED light is still reaching inside the detector enclosure
    • a high-power electronic appliance or machine (electromotor, fridge compressor etc.) could create too much electromagnetic interference radiation (EMI) - try changing the room or even the building

Please create a new GitHub issue if none of those tips did the trick. Alternatively, consider asking a local maker space or fab-lab for support, they'll be likely glad to help. :-)

The hardware design and documentation in this Wiki are licensed under the CERN Open Hardware License v1.2. Please refer to the usage guidelines of the license for further details. The software is provided under the terms of the BSD license.
General project overview in main readme, scientific background in corresponding paper.

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