First this to say is please post the url to your project. It saves people having to search for it on your home page. Second thing is that you have a 100R resistor in series with the 12V supply with no decoupling capacitance on the "downstream" or load side of the resistor so **everything** on the downstream (i.e. the relay coil) side of it will see it's supply step from almost 12V down to somewhere between about 9V and 8.25V when the relay is energised and tries to draw it's rated 30mA - 37.5mA from 12V. The relay is only rated to pull in with a voltage of 9V (75% of the reated 12V) so it is possible that your relay will not pull in correctly or may jitter. See the relay datasheet: [https://datasheet\.lcsc\.com/szlcsc/1810281710\_HTV\-Ningbo\-Bo\-Yue\-Elec\-HT3F\-12VDC\-SHG\_C22022\.pdf](https://datasheet.lcsc.com/szlcsc/1810281710_HTV-Ningbo-Bo-Yue-Elec-HT3F-12VDC-SHG_C22022.pdf) If you want to limit the relay current then connect the whole circuit to 12V and just put the 100R in series with the top end of the relay coil with about 2200uF from the 100R to ground so that the realy has 12V for at least the 10ms pullin time before the voltage across it's coil sags to around 8.25V or so. But if all you want to do is drive a buzzer, why do you need a relay when you can switch it on and off directly using a transistor? If it draws more current than a 2N2222 can handle, use an N channel power MOSFET. Relays just so 19th century.

I get what the problem is. You think this is a problem:  It's not. Please read the message at the lower left of the Design Manager screen and then read: [https://easyeda.com/forum/topic/Understanding-Ratlines-371bdbf646c54b23a57451eb05b2026d](https://easyeda.com/forum/topic/Understanding-Ratlines-371bdbf646c54b23a57451eb05b2026d)

Regarding : [https://easyeda.com/search?wd=Hall%20sensor%202%20x%20transistor](https://easyeda.com/search?wd=Hall%20sensor%202%20x%20transistor) Thank you for your comments. I have built the circuit  on vero board , it's a rats nest and as  you mention the relay chatters. But that is not the problem. I understand about ratlines, but the topic gives no solution. The footprints of the components should give no problem for a 2 sided  board. The auto router (on my laptop) starts up and a second later shuts down due to the the faulty showing 'nets' I have one more project in the pipeline and it has the exact same problem -->ALL faulty nets So. i am back to my original question " How to fix the 'faulty'  nets Thank you.

@bowsprit, What happens if you route it by hand?

Routing by hand works , but it's a bit tedious and prone for making mistakes. Practice makes perfect, Yes, I know.. Using the same circuit, I tried the local auto router on Win7-32  & win10-64, -->It just wont work on either, -->There must be a reason for it. ??

@bowsprit, @UserSupport, Sorry this is taking so long but I think I can see your problem now. I have tried deleting a few components from the PCB and then running the autorouter but that makes no difference. I have no idea what might be wrong but by accident, I may have found a workaround. **If you watch the video below you can see that the local autorouter does nothing (in fact after a while it does insert one track but then it does nothing else).** **If you then start a second run of the local autorouter, almost as soon as the message box saying you can't start a second instance of the autorouter while the first one is running, the first autorouter run completes successfully!**  * Note that this trick does not seem to work with the cloud autorrouter.

**Great that  trick works well on the local auto router** Many thanks [andyfierman](https://easyeda.com/andyfierman) for all your suggestions, time and effort --> I am a happy chappy again.