Electronics > Projects, Designs, and Technical Stuff
No way of bypassing this Lasertrigger circuit - and about calculating stuff
<< < (3/4) > >>
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       
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod