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lab:pigi:hardware [2013/07/23 19:08] – [Signals] chrono | lab:pigi:hardware [2023/04/19 13:56] (current) – [High Voltage] chrono | ||
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====== PiGI Hardware ====== | ====== PiGI Hardware ====== | ||
- | **Schematic** | + | **Schematic |
{{: | {{: | ||
~~CL~~ | ~~CL~~ | ||
- | **Layout** | + | **Layout |
{{: | {{: | ||
{{: | {{: | ||
{{: | {{: | ||
+ | |||
+ | **Prototype PCB's V1.0** | ||
+ | |||
+ | {{: | ||
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| T1 | NPN transistor with a >=1kV collector-emitter breakdown voltage | [[https:// | | T1 | NPN transistor with a >=1kV collector-emitter breakdown voltage | [[https:// | ||
- | The inductor is a high Q wound dust core choke with shielding to minimize EMI. The output voltage is set by the maximum current, which is controlled by the adjustable trimmer (R10) in the emitter lead of the STN0214. A lower resistor value (turning CCW) wil result in higher output voltage. Alternatively, | + | The inductor is a high Q wound dust core choke with shielding to minimize EMI. The output voltage is set by the maximum current, which is controlled by the adjustable trimmer (R10) in the emitter lead of the STN0214. A lower resistor value (turning CCW) will result in higher output voltage. Alternatively, |
Based on the CMOS 555 | Based on the CMOS 555 | ||
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Each impulse will pull the selected (J1/J2) GPIO pin to ground via T3 so that it's possible to generate an interrupt which can be counted. This ensures the safety of the PI and also helps to prevent getting false events generated by external EMI. | Each impulse will pull the selected (J1/J2) GPIO pin to ground via T3 so that it's possible to generate an interrupt which can be counted. This ensures the safety of the PI and also helps to prevent getting false events generated by external EMI. | ||
- | **Cathode connection preferred: | ||
- | It seems, that in practice (industrial/ | + | ===== Prototype |
- | + | ||
- | For optimal tube operation R3 (anode resistor) and the equivalent of R7/R8 (cathode resistor) | + | |
- | should have a 45:1 Ratio, at least that seems to have become " | + | |
- | + | ||
- | The same thing goes for the high voltage: It's rather hard to measure precisely without special high impedance probes but it was no problem in the end, as the high voltage range of the module is more than adequate and most tubes are very tolerant. In conclusion: It will work even if things aren't optimally aligned and by using a little knowledge and fine tuning, it provides perfect conditions for a particular geiger-müller tube. | + | |
- | + | ||
- | + | ||
- | ==== Prototype/ | + | |
- | + | ||
- | {{: | + | |
|< 100% >| | |< 100% >| | ||
^ Volume ^ PCB ^ Parts ^ Soldering method ^ Risk margin ^ Final product ^ | ^ Volume ^ PCB ^ Parts ^ Soldering method ^ Risk margin ^ Final product ^ | ||
| 7 V1.0 Prototypes | EUR 7,23 | EUR 8,67 | Hand (EUR 0) | --- | EUR 15,90 | | | 7 V1.0 Prototypes | EUR 7,23 | EUR 8,67 | Hand (EUR 0) | --- | EUR 15,90 | | ||
- | | < 100 V1.1 | EUR | EUR 9,84 | Hand (EUR 0) | 20% | TBD | | + | | < 100 V1.1 | EUR 4,97 | EUR 9,70 | Hand (EUR 0) | 20% | TBD | |
- | | >= 100 V1.1 | EUR | EUR 5,57 | Outsourcing (TBD) | 15% | TBD | | + | | >= 100 V1.1 | EUR 2,79 | EUR 7,05 | Outsourcing (TBD) | 15% | TBD | |
- | | >= 1000 V1.1 | EUR | EUR 3,82 | Outsourcing (TBD) | 10% | TBD | | + | | >= 1000 V1.1 | EUR 0,70 | EUR 3,95 | Outsourcing (TBD) | 10% | TBD | |
+ | |||
+ | As we can see, it scales very well with numbers and a non-profit oriented production run could bring many modules to people for less than 20 EUR. If it were sold for more than 25 EUR (fully assembled), someone would really be ripping people off. | ||
===== Assembly Instructions ===== | ===== Assembly Instructions ===== | ||
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=== Bottom === | === Bottom === | ||
- | |< 100% 5% 15% 60% 20% >| | + | |< 100% 5% 8% 8% 59% 20% >| |
- | ^ # ^ ID ^ Part/Value ^ Package | + | ^ # ^ |
- | | 1 | D2 | MMSD4148 | | | + | | 1 | D2 || MMSD4148 | | |
- | | 2 | C4 | 1nF | 0805 | | + | | 2 | C4 || 1nF | 0805 | |
- | | 3 | R5 | 330 ohms | 0805 | | + | | 3 | R5 || 330 ohms | 0805 | |
- | | 4 | R4 (R1 V1.0) | 100k | 0805 | | + | | 4 | R1 |
- | | 5 | R6 | 220k | 0805 | | + | | 5 | R6 || 220k | 0805 | |
- | | 6 | R1 (R4 V1.0)| 1k | 0805 | | + | | 6 | R4 |
- | | 7 | R9 | 27k | 0805 | | + | | 7 | R9 || 27k | 0805 | |
- | | 8 | IC1 | TLC555QDRQ1 - Case mark facing towards R6 | SOIC-8 | + | | 8 | IC1 || TLC555QDRQ1 - Case mark facing towards R6 | SOIC-8 |
- | | 9 | T2 | MMBT4401 | SOT-23 | + | | 9 | T2 || MMBT4401 | SOT-23 |
If you're not stacking two modules use either a 0-ohm resistor/ | If you're not stacking two modules use either a 0-ohm resistor/ | ||
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=== Top === | === Top === | ||
- | |< 100% 5% 15% 60% 20% >| | + | |< 100% 5% 8% 8% 59% 20% >| |
- | ^ # ^ ID ^ Part/Value ^ Package | + | ^ # ^ |
- | | 1 | C5 | 330pF | 0805 | | + | | 1 | C5 || 330pF | 0805 | |
- | | 2 | R7 | 1.5k | 0805 | | + | | 2 | R7 || 1.5k | 0805 | |
- | | 3 | R8 | 100k (default - see circuit description | + | | 3 | R8 || 100k (default - see [[# |
- | | 4 | T3 | MMBT4401 | SOT-23 | + | | 4 | T3 || MMBT4401 | SOT-23 |
- | | 5 | C1 | 220uF/10 | see BRD | | + | | 5 | C1 || 220uF/10V LowESR Aluminium Electrolytic Capacitor |
- | | 6 | C2 | Vishay MLCC 10nF/1kV | 1206 | | + | | 6 | C2 || Vishay MLCC 10nF/1kV | 1206 | |
- | | 7 | C3 | Vishay MLCC 10nF/1kV | 1206 | | + | | 7 | C3 || Vishay MLCC 10nF/1kV | 1206 | |
- | | 8 | R2 | KOA Thick Film 1M 0.25W 0.5% | 1206 | | + | | 8 | R2 || KOA Thick Film 1M 0.25W 0.5% | 1206 | |
- | | 9 | R3 | KOA Thick Film 4.7M 0.25W 1% | 1206 | | + | | 9 | R3 || KOA Thick Film 4.7M 0.25W 1% | 1206 | |
- | | 10 | D1 | Vishay BYGM23 Fast Recovery Diode 1.5A/ | + | | 10 | D1 || Vishay BYGM23 Fast Recovery Diode 1.5A/ |
- | | 11 | T1 | STN0214 Bipolar NPN 1k2V | SOT-223 | + | | 11 | T1 || STN0214 Bipolar NPN 1k2V | SOT-223 |
- | | 12 | L1 | Murata Shielded Inductor 15mH | see BRD | | + | | 12 | L1 || Murata Shielded Inductor 15mH | see BRD | |
- | | 13 | R10 | Bourns Trimmer 100R | see BRD | | + | | 13 | R10 || Bourns Trimmer 100R | see BRD | |
- | | * | R10a | optional, with a fixed value instead of R10 | 0805 | | + | | * | |
- | | 14 | H1 | [[http:// | + | | 14 | H1 || [[http:// |
===== Test Points ===== | ===== Test Points ===== | ||
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This test was run on a V1.0 prototype board, plugged into a Pi with running counterd. A radioactive test source (thorium) was placed in front of a FHZ-76 tube. The high-voltage was increased (turning R10 counter-clockwise) until the count-rate reported by counterd didn't increase anymore. The following table shows the resulting measurement of the set voltage using different setups: | This test was run on a V1.0 prototype board, plugged into a Pi with running counterd. A radioactive test source (thorium) was placed in front of a FHZ-76 tube. The high-voltage was increased (turning R10 counter-clockwise) until the count-rate reported by counterd didn't increase anymore. The following table shows the resulting measurement of the set voltage using different setups: | ||
+ | |< 100% >| | ||
^ Resistor Setup ^ Read Voltage ^ Calculated Voltage ^ | ^ Resistor Setup ^ Read Voltage ^ Calculated Voltage ^ | ||
| 10M (Fluke-87V internal resistor) | 230V | 230V | | | 10M (Fluke-87V internal resistor) | 230V | 230V | | ||
| 10M + 42.3M (9x 4.7MOhm in series) | 63.7V | 333V | | | 10M + 42.3M (9x 4.7MOhm in series) | 63.7V | 333V | | ||
- | | 10M + 1G ([[http://www.highvoltageshop.com/ | + | | 10M + 1G ([[http:// |
Measured at: [+] Cathode of D1 (pin facing towards R2) [-] Cathode of GM Tube (HV- Pad) | Measured at: [+] Cathode of D1 (pin facing towards R2) [-] Cathode of GM Tube (HV- Pad) | ||
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**Formula** | **Formula** | ||
- | <x> | + | <m> |
V_actual = V_read * {{ R_meter + R_probe } / R_meter} | V_actual = V_read * {{ R_meter + R_probe } / R_meter} | ||
- | </x> | + | </m> |
**Examples** | **Examples** | ||
- | <x> | + | <m> |
63.7V * {{10 MOhm + 42.3 MOhm} / {10 MOhm}} \approx 333V | 63.7V * {{10 MOhm + 42.3 MOhm} / {10 MOhm}} \approx 333V | ||
- | </x> | + | </m> |
- | <x> | + | <m> |
4.56V * {{10 MOhm + 1000 MOhm} / {10 MOhm}} \approx 460V | 4.56V * {{10 MOhm + 1000 MOhm} / {10 MOhm}} \approx 460V | ||
- | </x> | + | </m> |
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{{: | {{: | ||
+ | |||
+ | === Tube === | ||
+ | |||
+ | It seems, that in practice (industrial/ | ||
+ | |||
+ | For optimal tube operation R3 (anode resistor) and the equivalent of R7/R8 (cathode resistor) | ||
+ | should have a 45:1 Ratio, at least that seems to have become " | ||
+ | |||
+ | ** Worst Scenario (Undervoltage & very high anode/ | ||
+ | |||
+ | {{: | ||
+ | |||
+ | ** Recommended operating voltage & 45:1 anode/ | ||
+ | |||
+ | {{: | ||
+ | |||
=== GPIO output === | === GPIO output === | ||
- | {{:lab:pi-gi-v1.0-dso-gpio-output-0.5v-20us.png|DSO Trace of the falling edge on the GPIO Line}} | + | This is how the final impulse signal looks like to the counting IO Pin. It also leaves a question: For the LND 712 the dead-time is supposed to be 90us, but when you count the divs in the scopeshot above it is about 140us. Shouldn' |
- | <WRAP round help> | + | {{:lab:pi-gi-v1.0-dso-gpio-output-0.5v-20us.png|DSO Trace of the falling edge on the GPIO Line}} |
- | This is how the final impulse signal looks like to the counting IO Pin. It also leaves a question: For the LND 712 the dead-time is supposed to be 90us, but when you count the divs in the scopeshot above it is about 160us. Shouldn' | + | |
- | </ | + | |
===== Radioactive Test Sources ===== | ===== Radioactive Test Sources ===== | ||
- | Since everything is regulated these days up to the point that only multi-national-companies | + | Since everything is over-regulated these days, up to the point where only multi-national-corporations |
The mightyohm blog has compiled a list of things you can try to use: | The mightyohm blog has compiled a list of things you can try to use: |