26 votes

How can a reed switch be used for high current applications?

Don't use the reed switch directly. Use the reed switch to switch the coil of a larger relay. Alternatively, use the reed switch to switch the gate of a FET large enough to handle to load current.
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19 votes

How can a reed switch be used for high current applications?

For long-term reliability, a 60 A load requires relay contacts rated for at least 100 A. The coil current for such a contactor almost certainly is greater than the reed switch rating. There are at ...
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11 votes

What kind of tactile switch is this?

This is a familiar feature in DSLR shutter controls- partial press for focus and full press for shoot. Here is a lower profile switch from (major Japanese switch manufacturer) ALPS. They call it a &...
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11 votes

What is the ideal method of sensing whether 4 points on the bottom of a device are all depressed to indicate contact?

Limit switches might be better options than momentary make push buttons, as they can have longer travel and usually require less force to depress. They are extensively used in things like industrial ...
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  • 1,316
6 votes
Accepted

Two power sources and two outputs with one switch

Here's a schematic diagram which includes a double-pole single-throw (DPST) switch that should, as @Eugene commented, do what you need: simulate this circuit – Schematic created using ...
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6 votes

What is the ideal method of sensing whether 4 points on the bottom of a device are all depressed to indicate contact?

Security sensors need specs for a baseline for reliability expectations such as conditions that cause a false positive and true negative, then design around these probabilities to choose a true ...
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5 votes

What kind of tactile switch is this?

The behavior is called "double action" by many manufacturers. A not uncommon feature. The size and packaging and specifics of the connections will vary by manufacturer and model and thats a ...
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4 votes

What is the ideal method of sensing whether 4 points on the bottom of a device are all depressed to indicate contact?

An near-infrared LED can be paired with a phototransistor. They will work behind a plastic panel or inside a plastic foot or or potted in an epoxy foot. And most common plastics and epoxies are ...
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4 votes

What is the ideal method of sensing whether 4 points on the bottom of a device are all depressed to indicate contact?

You could use an accelerometer placed inside the PC case. The accelerometer could be used to detect if someone moved the unit more than a certain amount. Essentially integrate acceleration to find ...
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  • 9,542
3 votes

What is the ideal method of sensing whether 4 points on the bottom of a device are all depressed to indicate contact?

If what you actually want to achieve is ensuring that the computer cannot be taken away from the desk without encrypting the hard drive, this will work at minimal cost: Enable BitLocker with a pre-...
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3 votes
Accepted

What could be wrong if neutral has power?

Here's the fan schematic with a standard switch. The only difference with a smart switch is the additional neutral connection. Please recheck and rewire.
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  • 9,638
3 votes

Why is this transistor in my bootstrap driver failing?

It appears your breadboard has the transistors wired incorrectly. The 2N5551 & 2N5401 datasheets show a EBC pinout (looking at the front face) but you have wired as CBE. From memory the CBE is the ...
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  • 190
3 votes

Why is this transistor in my bootstrap driver failing?

A couple of items in the design are not ideal: The upper transistor is not driven heavily enough. When the input transistor is turned off current from the 6.8k resistor will enter the base of the ...
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2 votes
Accepted

Ethernet Switch IC

It is a switch and that is how Ethernet works, it is a packet switched network, so the purpose of the switch chip is to switch packets between interfaces. All three ports are gigabit, and if it says ...
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2 votes

Ethernet Switch IC

If the two copper ports are forwarding 500Mb/s to each other AND 500Mb/s to the GMII port then all three ports are fully loaded so yea it can make sense. If ports 1 and 2 are copper and 3 is GMII then ...
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2 votes

How can I combine 4 separate bits into one 4 bit output?

You need no additional logic. You can view four 1-bit wires as one 4-bit signal. Just make sure that you get the order correct, which bit is least significant, and so on.
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  • 1,163
2 votes

Why is this transistor in my bootstrap driver failing?

First: Your input transistor is likely missing a base resistor. You do want a base resistor if your control signal is a voltage (as opposed to a current). Your schematic looks reasonable. Your problem ...
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  • 1,091
2 votes

Two power sources and two outputs with one switch

It's possible. Here's the schematic.
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  • 9,638
2 votes

What is the ideal method of sensing whether 4 points on the bottom of a device are all depressed to indicate contact?

If you select a momentary-contact pushbutton with an extra few millimeters of travel (before the contact disengages), you can arrange so that with the PC on the surface, the button is not fully ...
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  • 7,070
2 votes

An over- and under-voltage protection system

The 555 timer IC contains a comparator (two, actually) so it's possible to coax it into acting as a under/over voltage detector if you power it from a regulated (reference) voltage. Here is one ...
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1 vote
Accepted

Simplest solution to automatically turning off dash cam when ignition is off, but turn it on with button?

Here are a couple of options. Option A: It looks like the ignition wire acts as an inhibitor that keeps the camera from recording when it has 12v. You could use a switch (SPDT) to connect it to 12v ...
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  • 462
1 vote

Circuit that switches on at 4V and off at 3V

Try this for a start. It is important that the circuit itself draws low current from the cell. This circuit is cheap and acceptable exact. A diode is used as reference voltage here, this has a ...
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  • 31
1 vote

How can a reed switch be used for high current applications?

You will want a protection circuit (or BMS, stands for Battery Management System) for the LiPo pack, to implement overtemperature and overcurrent cutoff. The protection circuit will have a MOSFET that ...
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  • 4,670
1 vote

Switching stereo input between three stereo outputs

Just to be sure you've got the right switch, it should have 8 contacts / terminals in two groups of 4. In each group of 4 there will be 3 input contacts (call them A,B & C) and one output which ...
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1 vote

How can I combine 4 separate bits into one 4 bit output?

In hardware, it needs to be a Parallel to Series Output (PISO) Shift Register (SR) or a digital 4:1 MUX. 4 bits is rather inefficient for PISO's as they are usually 8 bit devices, but let me show you ...
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1 vote
Accepted

Ethernet Switch configuration mode

The answer is on page 44: 4.5.2 MAC INTERFACE CLOCKS The MII interface is clocked asymmetrically, with the PHY device driving both the RX_CLKx receive clock and the TX_- CLKx transmit clock to the ...
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  • 1,108
1 vote

Switch off 2 power supplies using a single switch in a feedback loop

One way to make this work is to split the LEDs to only the way one is powered off of the second battery. In this case, you can use the switched first battery to operate the relay, acting as the switch ...
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  • 7,070
1 vote

Switch off 2 power supplies using a single switch in a feedback loop

The lights look great! I have done similar things in my house. Is it possible to increase the voltage, if not ok. In my proposed solution the increase in voltage will reduce the current in the wire ...
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  • 2,533
1 vote

Momentary switch to activate 555 timer

This sounds like a problem people had when trying to connect a reset switch to a Commodore 64 computer, if the switch was held down it would keep it in reset mode (which wasn't good for the CPU). The ...
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  • 3,386
1 vote
Accepted

Help with capacitive touch button output configuration

It's a bit confusing because it says NPN but they actually have a MOSFET in there and list drain to source resistance in the electrical characteristics. NPN is a quasi-generic term for a switching ...
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