One of my little copy/paste projects died again (a 12V 1 A circuit - last time it died). Now it was a short that caused it.

Is there a simple way of keeping my parts from burning? By simple I mean something like a resistor that will burn before more expensive parts will, and that will cause the circuit to stop receiving power.

Also what are the problems that come with being simplistic?

Edit 1: So the circuit after all the answers looks like this:

enter image description here

  • 1
    \$\begingroup\$ \$30\:\text{V}\$ (AC and/or DC) seems excessive for a \$12\;\text{V}\$ relay. Is this the actual situation you need to cope with? \$\endgroup\$
    – jonk
    Nov 1, 2019 at 6:37
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    \$\begingroup\$ Is there a simple way of keeping my parts from burning? Sure! Operate them within their rated parameters! If what jonk says is true and you do operate a 12 V rated relay at 30 V then for sure you're asking for trouble. \$\endgroup\$ Nov 1, 2019 at 7:02
  • \$\begingroup\$ @Bimpelrekkie Since that time I have found a 15V AC/DC and after all the circuit it gives less. \$\endgroup\$
    – Joita Dan
    Nov 1, 2019 at 7:40
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    \$\begingroup\$ Hmm, so the actual circuit you're using isn't shown in the linked question either. Then your question is similar to: I build something, but I'm not showing you what it is, it has a problem, how do I solve it? What makes you think that we do not need a schematic of what you made? \$\endgroup\$ Nov 1, 2019 at 7:56
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    \$\begingroup\$ Because the linked circuit shows a 30V supply but your said you use 15V. \$\endgroup\$
    – Christian
    Nov 2, 2019 at 11:47

1 Answer 1


A simple resistor that burns before more expensive parts do is called a fuse. They are available for pennies at every major and minor electronics seller.

  • \$\begingroup\$ so where do I insert it, right at the + of the power supply? \$\endgroup\$
    – Joita Dan
    Nov 1, 2019 at 15:45
  • \$\begingroup\$ Yes. So that it protects at much as possible of your circuit \$\endgroup\$
    – Christian
    Nov 2, 2019 at 11:46
  • \$\begingroup\$ do I need to calculate the needed fuse? \$\endgroup\$
    – Joita Dan
    Nov 20, 2019 at 15:43
  • \$\begingroup\$ of course you do, you can't use the same fuse to protect a 10mA circuit as a 10 kA circuit. \$\endgroup\$
    – Christian
    Nov 21, 2019 at 13:16
  • \$\begingroup\$ Would a F2A250V be ok? This is what they gave me. This page recomends a 1A fuse. fusefactory.com.au/2019/08/23/… \$\endgroup\$
    – Joita Dan
    Nov 28, 2019 at 20:40

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