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A: bi-directional motor control using two mosfets

Andy akaHow is the board able to achive this with just two mosfets per motor? Right on the front page is the hint to how it does this: – The Dual DC Motor Driver 4A V3 allows to indipendently drive two DC motors, controlling both velocity and direction. The minimum supply voltage allowed is 7V, so you…Andy aka301k@DionysisSpinellis Yes I got the voltage stated incorrectly but my point is still valid. At the series junction of the two batteries is where one wire on the motor makes a connection. The other connection on the motor connects to the half bridge output hence, the motor can be driven forwards, backwards or anywhere in between. Do you follow? tlfong01I don’t follow. I think something goes wrong somewhere. Andy aka@tlfong01 does the added picture help? tlfong013722@Andy aka, Many thanks for your clarification. (1) I said I didn’t follow you because (a) I agree your center tapping two batteries trick is innovative, and might work, but I have never seen such a trick, so I said I didn’t follow because I am not sure if I understand your description of the circuit. (b) You picture confirms my understanding, so I could now follow your reasoning. But I am new to power MOSFET, so I need to to think hard to convenience me this trick works. I will report back later, might take some time. 🙂 Andy akaThink of the motor as a loudspeaker and the two MOSFETs as a push pull output stage in an audio power amplifier. Does that help? tlfong013722yst 23:04Ha, your first picture clarifies, but second picture confuses me again. You remind me that long time ago, I used NPN BJT and PNP BJT to form a complimentary pair to make a power amp, to push pull a loudspeaker. I vaguely remember that using one BJT needs to work in B region/mode/type, and if two BJTs working together, would work in A or C mode (I forgot). Nowadays everybody is using digital D type pwr amp. So I am hopeless out of day, but I don’t worry, because I can just buy a cheap D-type module, more HiFi, very small size, no heat sink, no decoupling cap, direct drive speaker / to cont … Andy akaThat’ll be “complementary” and not “complimentary” @tlfong01 tlfong013722Your complementary N-type P-type MOSFET does not seem to meet the OP’s requirement of only two same type MOSFETs to control direction of motor. But your push pull power amp with two diodes and the earlier two battery solution inspires me something. Let me go to the drawing board to think aloud my new design. See you later. PS – Your spelling lesson is indeed a compliment. Cheers. Andy akaThey are not MOSFETs and that picture was a “think of it as…” demonstration and not an equivalent to what the OP stated. tlfong013722

@Andy aka, I don’t know why you say: “They are not MOSFETs and that picture was a “think of it as.” I do not get this statement/idea/impression at all.

I now have a bad feeling. This reminds another weird question I saw recently. More about this later.

This this another question I found weird. Can I use a resistor before a fuse?

electronics.stackexchange.com/…

@codeBarrel, Welcome and nice to meet you. Ah, let me first introduce myself.

One of my hobbies is (1) Guessing the reason of why some one asks a question, (2) Guessing the reasons of why others make this or other replies.

Your question is bit hard to guess. Have a nice weekend. Cheers. – tlfong01 9 hours agoNothing urgent. Perhaps we would chat a couple of days later.  The last message was posted 12 hours ago.

.END

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