Transistor Instead of Relay for Car Horns

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Introduction: Transistor Instead of Relay for Car Horns

About: Autistic person who's interests include in utility cycling, recreational cycling, cycling safety, electronics, gardening, Arduino, and LEDs.

Instead of relays, you can use transistors for switching your car horns.

For my latest car horns for bicycles setup, I used an IRFZ44N N-channel MOSFET instead of a relay. MOSFETs use less current than relays and switch faster. So far, it seemed to work as well as relays. The pictures of my setup are in the next pages.

Step 1: Horn Setup

Step 2: Horns on Bicycle

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    3 Comments

    Its a long time since I played with electronics.( not this centuary) I had to stack 3 MOSFETs to handle the modest 18amps for an early experiment in electric flight. I see from the spec sheets that one can handle about 50amps, that makes things a lot more viable.

    1 reply

    And for the horn you even won't need any cooling since it switches only for a second or so. Else, for long time switching, you eventually need cooling if operating a MOSFET in its border range.

    That looks like a fun, easy one to save! :). Your bike project reminds me of when I had a Honda Helix scooter I had bought since a car wasnt in my budget but I wanted something new and reliable. The scoot was awesome but people on the freeway often dont see 2 wheelers :/. The factory horn, like those on most cars, SUCKED!!
    Soooooo I bought a set of air horns! Woo!! Mounted them under the rear fender well.
    Theres nothing like seeing a car coming into your lane because they didnt do a head check, hitting the horn button and watching someone poop their pants thinking a big rig is there!! Hehe