That is the body connection. All MOSFETs have a fourth connection to the substrate, but for discrete MOSFETs this is normally connected internally to the source which results in a parasitic body diode anti-parallel to the source-drain. So in a typical discrete MOSFET you see the body connection tied to the source terminal and you get the MOSFET symbol which ...
I think the magneto peak voltage is definitely too high for D1/D2, probably the optocoupler and maybe the MOSFET (no part numbers being provided).
Try replacing D1 with a 1N4007 and and replace the optocoupler/MOSFET with an opto-MOS SSR.
Edit (for general info): The objective is to replace this kind of "kill switch"
A magneto is a permanent ...
Pulled down internally means there is a pull-down resistor inside the chip. If it was an internal pull-up then you don't technically need an external pull-up resistor but may want one anyways for noise immunity.
Since it is a pull-down internally, you most definitely need an external pull-up resistor. The internal pull-down is probably a very high resistance ...
You can easily do that with the "SCH LIST" panel (right bottom of your Altium window).
1 - Select all your labels.
2 - Open SCH List
3 - Select the column Text
4 - Right click -> Smart Edit
5 - Set your changement
6 - Enjoy
If you look at the data sheet documentation for the LT4256, it also uses an IRF530 but, in that circuit, it relies on the internal bulk diode for any necessary reverse protection: -
I expect that the person designing this circuit may have been unsure about the presence of the internal MOSFET bulk diode and may just have played safe and included an extra one....
With the MOSFETs in SMD, how big must be the thermal pad of each MOSFET be if it must handle 5 amperes? The final MOSFET is an IRLZ44ZSTRLPBF.
There are too many unknowns to solve this mathematically. But to get you started:
irlz44zpbf datasheet bottom of page 1: "62
RθJA Junction-to-Ambient (PCB Mount) = 40°C/W". This means that for the minimum ...
You appear to have connected the regulator incorrectly.
From the datasheet:
You have 5V from the USB adapter going to pin 1. That's "Vout" according to the datsheet.
Connect your yellow wire to the right most pin of the regulator instead of the left most pin.
simulate this circuit – Schematic created using CircuitLab
Use the same rectifier LDO combo that worked for you. I just showed it as D1 C1, U1, C2, while R1, Q1 shorts the DC side of the AC bridge which is normally no-load to suppress the magneto voltage with 1.5V + 2 Ohms (Rce for PN2222A) which should be more than enough.
Estimated values depend on ...
Applying 3.3V to the regulator input will likely result in an unregulated output of <3.3V (3.1 to 2.7V based on power draw up to 150 mA) Its not a perfect pass through.
And while the regulator accepts up to 10V, you need to consider the voltage rating for anything else in the path, mainly capacitors, or in this case other ICs, or the LEDs. And voltage ...
The voltage between body and source modulates the drain current in similar fashion to the voltage between gate and source. The body behaves similarly to a JFET gate. For switching, it's generally fine to connect body connections to the power rails. But for linear circuits, you may want something different. For example, if the source voltage varies and the ...
A minimum of 5cm^2 / W of heavy copper or 2x this otherwise with standard copper heatsink is required.
this depends also on your maximum internal ambient and max desired reliability with junction temperatures and self heating of nearby e-caps.
Datasheets may give better formulae and recommended copper thickness and area, but this is my rule of thumb for ...
Decoupling caps are about low inductance, and inductance depends mostly on size. 100nF caps are used because they are cheap and small, but if your limit on capacitor size is what you are willing to solder, there is no reason to impose an artificially low limit on capacitance by using 100nF caps. So:
Think about the smallest package size you're comfortable ...
One common misconception in electronics is that a wire not connected to anything will have a voltage of "zero volts".
Most people seem to understand that in a typical circuit with lots of stuff connected to "+5V",
there should be one thing (typically a connector accepting power from some outside power source, or a battery connector, or ...