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I am making a circuit using a 4 pin hall sensor with arduino. It turns out that the hall sensor outputs a negative voltage as output, which arduino cannot read, so I will need a PNP transistor, I don't have one but I have a bunch of NPN (BC547) laying around. Is there any way I can make a PNP transistor or add circuitry to make the NPN into PNP? Thanks in advance. For more info about the hall sensor, the first pin is +ve second is Normally open third is Normally closed and fourth is -ve Schematic

Turns out that I have a pnp transistor with my Snap Circuits kit. I cracked it open, soldered some wires and now, it looks like this image Take a look at my Schematic above and tell if I need another resistor or somethin

SamGibson
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Bheeshma
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  • I also want to make a circuit with arduino and a ir sensor which also turns out that it outputs negative voltage. So I need this very badly – Bheeshma Apr 07 '21 at 03:30
  • In principle, you can do it. Show us the circuit. – Enrico Migliore Apr 07 '21 at 03:33
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    Wrong question - you want to convert your signal to something useful for the Arduino. Converting pno into npn is not the issue. – Kartman Apr 07 '21 at 03:38
  • Tell us exactly which hall sensor you're using, and give us a link to the datasheet. Someone here will figure it out for you, and most likely you don't need any transistors at all. – brhans Apr 07 '21 at 03:59
  • you can probably connect that sensor directly, but you haven;t described it in enough detail for me to say how. – Jasen Слава Україні Apr 07 '21 at 05:18
  • Can you explain more closely what signal range your sensor generates? It's very unlikely its output is outside the range of GND-VCC – PMF Apr 07 '21 at 06:11
  • Short answer: you can't switch transistor polarity. Also I *really* doubt your sensor is giving out a negative voltage (a JFET could be the solution in that unrealistic case). Do you have a datasheet for the sensor? – Lorenzo Marcantonio Apr 07 '21 at 06:22
  • The hall sensor is used in pc fan and I am not able to find a datasheet. What I do know is it's behaviour, it closes Normally open when it is exposed to the North pole of a magnet and opens it when its exposed to south pole. – Bheeshma Apr 07 '21 at 13:26
  • @Lorenzo Marcantonio -ve voltage means ground – Bheeshma Apr 07 '21 at 13:29
  • Schematic has been uploaded – Bheeshma Apr 07 '21 at 14:02
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    @Bheeshma: The schematic is private on your Google drive - no one else can see it. – JRE Apr 07 '21 at 14:07
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    @Bheeshma - Please stop using Google Drive links for your schematics. (a) As already commented, you are providing *private* links, which means we cannot see your schematics. (b) When those links become unavailable in future, then the question becomes useless. || Therefore please use the site's built-in image upload capability. Click [edit] then hit Ctrl+G (on a PC) (or click the "mountains" icon above the edit box) and follow the on-screen instructions to upload the image(s). Images need scaling to be no larger than 2MB before uploading. Thanks. – SamGibson Apr 07 '21 at 15:07

2 Answers2

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No. You can't change an npn transistor into a pnp transistor.

Hearth
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NPN transistor can't be converted into PNP transistor. This question is already discussed here. How can I convert a PNP to NPN transistor?

mastermind
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