| Electronics > Projects, Designs, and Technical Stuff |
| No way of bypassing this Lasertrigger circuit - and about calculating stuff |
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| HendriXML:
--- Quote from: mycroft on January 15, 2019, 01:42:51 pm ---Beware of real life! In real life a fly or a leaf can interrupt the beam. You will have too many false positives! --- End quote --- Purely hypothetical, because the circuit is not really worth defending... If a fly crosses the beam it should signal that, that is not really a false possitive in regard to this circuit. If there would be exceptions / margins at this level, then it is also more vulnerable against attack’s. At a higher level when processing the output of this circuit one could define rules that take more things in account. Maybe 2 beams out of 10 should be signaled to set an alarm. Also I hate flies so I don’t want them to intrude as well :). |
| HendriXML:
--- Quote from: tggzzz on January 15, 2019, 01:57:56 pm ---In every system where safety is in question, you should concentrate on how the system can fail. That's much more difficult than how the system works. Understanding that is a key difference between professional engineering and amateur tinkering. Start by understanding that extra complexity means extra failure mechanisms. Continue by determining what will happen if a component or connection fails. And don't forget to consider all the things that are outside the system. --- End quote --- Your absolutely right. This circuit is amateurish and for study only, and I really like it in that regard. Installing laserbeams for protection is not very practical. And has very little WAF. You should see my other circuit: https://www.eevblog.com/forum/projects/bi-regulated-power-supply/ That one is too sensitive and prone to failure as well, it would really give you the shivers. But is also an exploration of possibilities. One should allow themselves to do projects like that as well. And maybe only thoose before having sufficient skills. |
| HendriXML:
--- Quote from: xani on January 15, 2019, 01:00:40 pm ---Clearly if you want max security you should instead beam AES-encoded and signed (or even go whole hog with ECDH and public/private key encryption) stream that sends ever-increasing number(to avoid replay attack) to the receiver 8) --- End quote --- I think random signals would suffice as well, ‘cause the end point knows what to expect! In both cases the system could be attacked by copying the laser pulses. But that can be made very hard to implement when the sensor is in a thin tube. The copying laser in that case won’t be able to hit the sensor without blocking the sytems one. |
| HendriXML:
:PI added functionality to my BOM reporter (just another script in the same tool) to merge calculated values in the designator report as well. If calculated values exists, they are reported on a second line. Specifications can also include powerratings, voltage ratings, etc. This way lots of information can be packed in to a single report. Another tab, the actual BOM report shows where stuff is located and how much (PartKeepr), I'll post that as well. By reporting the max current / voltage a resistor can take, it is easy to check which resistors might be at risk and do a calculation of its power consumption. The E-series are shown, because I prefer to use lower E-serie values over higher ones, because then its easer to maintain a stock. |
| HendriXML:
Designator specifications C1 10nF E3 50V ceramic THT capacitor D1 LED led D2 3,3V E6 1W 303mA zener diode D3 LDD photodiode D4 1N4004 diode D5 LED led D6 1N5817 schottky diode D7 LED led D8 1N5817 schottky diode D9 1N5817 schottky diode D10 1N5817 schottky diode D11 1N5817 schottky diode D12 1N5817 schottky diode Q1 2N7000 n-mosfet Q2 2N7000 n-mosfet Q3 2N3906 pnp transistor Q4 2N3904 npn transistor Q5 2N3906 pnp transistor Q6 2N7000 n-mosfet Q7 2N7000 n-mosfet R1 56Ω E12 250mW 3,74V|66,8mA 2% metal film THT resistor 56Ω E12 R2 1,8kΩ E12 250mW 21,2V|11,7mA 2% metal film THT resistor 1,8kΩ E12 R3 100kΩ E3 250mW 158V|1,58mA 2% metal film THT resistor 100kΩ E3 R4 68Ω E6 250mW 4,12V|60,6mA 2% metal film THT resistor 68Ω E6 R5 4,7kΩ E3 250mW 34,2V|7,29mA 2% metal film THT resistor 4,7kΩ E3 R6 47kΩ E3 250mW 108V|2,3mA 2% metal film THT resistor 47kΩ E3 R7 47kΩ E3 250mW 108V|2,3mA 2% metal film THT resistor R8 12kΩ E12 250mW 54,7V|4,56mA 2% metal film THT resistor R9 180Ω E12 250mW 6,7V|37,2mA 2% metal film THT resistor R10 51kΩ E24 250mW 112V|2,21mA 2% metal film THT resistor R11 4,7kΩ E3 250mW 34,2V|7,29mA 2% metal film THT resistor R12 1,8kΩ E12 250mW 21,2V|11,7mA 2% metal film THT resistor 1,8kΩ E12 R13 56Ω E12 250mW 3,74V|66,8mA 2% metal film THT resistor 56Ω E12 R14 470Ω E3 250mW 10,8V|23mA 2% metal film THT resistor 470Ω E3 R15 12kΩ E12 250mW 54,7V|4,56mA 2% metal film THT resistor 12kΩ E12 R16 27kΩ E12 250mW 82,1V|3,04mA 2% metal film THT resistor 27kΩ E12 R17 82kΩ E12 250mW 143V|1,74mA 2% metal film THT resistor 82kΩ E12 R18 33kΩ E6 250mW 90,8V|2,75mA 2% metal film THT resistor 33kΩ E6 R19 4,7kΩ E3 250mW 34,2V|7,29mA 2% metal film THT resistor R20 39kΩ E12 250mW 98,7V|2,53mA 2% metal film THT resistor 39kΩ E12 R21 150Ω E6 250mW 6,12V|40,8mA 2% metal film THT resistor 150Ω E6 R22 12kΩ E12 250mW 54,7V|4,56mA 2% metal film THT resistor R23 4,7kΩ E3 250mW 34,2V|7,29mA 2% metal film THT resistor 4,7kΩ E3 R24 4,7kΩ E3 250mW 34,2V|7,29mA 2% metal film THT resistor R25 100kΩ E3 250mW 158V|1,58mA 2% metal film THT resistor R26 4,7kΩ E3 250mW 34,2V|7,29mA 2% metal film THT resistor R27 33kΩ E6 250mW 90,8V|2,75mA 2% metal film THT resistor 33kΩ E6 R28 27kΩ E12 250mW 82,1V|3,04mA 2% metal film THT resistor 27kΩ E12 R29 12kΩ E12 250mW 54,7V|4,56mA 2% metal film THT resistor 12kΩ E12 R30 82kΩ E12 250mW 143V|1,74mA 2% metal film THT resistor 82kΩ E12 R31 39kΩ E12 250mW 98,7V|2,53mA 2% metal film THT resistor 39kΩ E12 R32 75Ω E24 250mW 4,33V|57,7mA 2% metal film THT resistor 75Ω E24 R33 4,7kΩ E3 250mW 34,2V|7,29mA 2% metal film THT resistor R34 4,7kΩ E3 250mW 34,2V|7,29mA 2% metal film THT resistor R35 100kΩ E3 250mW 158V|1,58mA 2% metal film THT resistor RV1 1kΩ E3 variable resistor 1kΩ E3 RV2 5kΩ variable resistor RV3 500Ω variable resistor 500Ω SW1 Reset latch component SW2 SW_Push component U1 TL082 op amp U2 LM339 comparator U3 LM339 comparator |
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