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Forum Index : Microcontroller and PC projects : picoMite Mini
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TheRockGod Newbie Joined: 01/04/2022 Location: AustraliaPosts: 8 |
Thanks all...I put my transistors in contrary to the silk screen...and they work! Of course, because mosfets will conducts in both directions...So, I assumed this to be correct. I stand corrected. At any rate, the board works well...now I'm awaiting the expansion boards to arrive. Many thanks for a great board design. Tony |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 1722 |
"I put my transistors in contrary to the silk screen...and they work!" Could be risky. Most MOSFETS have a diode from drain to source. If the anode is on the 5V side the voltage on the Pico pins may be too high. Measure them to be sure. |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5648 |
What looks to be a better substitute for the 2N7000 would be the VN10KN3-G, which has the same pinout but VGS(th) is 2.5V. It'll be less "borderline". The 2N7000 can be as high as 3V - it'll probably work most of the time. Re. connections. Now I don't know what to believe. ST data sheet https://www.st.com/resource/en/datasheet/cd00005134.pdf Labels pins 1-2-3 as Source-Gate-Drain Same as Vishay https://www.vishay.com/docs/70226/70226.pdf (who point out that BS170 is the reverse way round) Microchip also agree https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/2N7000-N-Channel-Enhancement-Mode-Vertical-DMOS-FET-Data-Sheet-20005695A.pdf ONsemi datasheet https://www.onsemi.com/pdf/datasheet/nds7002a-d.pdf Labels pins 1-2-3 as Drain-Gate-Source Looks like ONsemi have it wrong. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 1722 |
"Now I don't know what to believe." Safest thing is to measure D-S with multimeter diode range. No matter what the data sheets say you will then know for sure. With the 2N7000s I have the left pin goes to the Pico and the right to the pullup / PS2 - Flat side facing you, legs pointing down. . Edited 2022-05-06 10:46 by phil99 |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5648 |
That would be Source-Gate-Drain then. Sounds right. :) Edited 2022-05-06 17:32 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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