Tagged Questions

0
votes
0answers
26 views

over temperature and current limiting question about a power switch: BTS5235

I am designing a cuircuit with BTS5235-a smart power switch from infineon.this is the datasheet of BTS5235 I get realy confused about its datasheet. 1.problem about VDS(Voltage at power transistor). ...
2
votes
2answers
73 views

Best practice to switch +V or GND connection?

Consider LAMP1 and LAMP2 in the simple example circuit below: Which is the "better" practice, using the switching component ...
0
votes
1answer
54 views

Any Ideas for Understand one of the 3 phases has powered

I want to ask you about a situation which i couldnt find the exact solution or better way to do the job. The situation is i have 3 phase (380V) induction motor and one of the phases to the motor had a ...
6
votes
4answers
217 views

Protecting Microcontroller Input Pins from Soft Power Switch

I'm working on a soft power switch for a microcontroller where a momentary switch can turn the circuit on (including microcontroller), and then when the switch is pushed a second time, the ...
6
votes
2answers
138 views

How do these modern power buttons on devices work

In the older days and still now we have buttons where one way is off and the other way is on, its mechanically built to connect or disconnect an electric path physically. On modern devices like ...
3
votes
3answers
121 views

How can I switch a high current with a low-rated switch?

I'm designing and building a breadboard power supply for myself, which draws power from an ATX-like SMPS (Mains in, single Molex plug out) via a 4-pin Molex connector. The design includes a switch to ...
2
votes
2answers
124 views

Need help designing a custom box

I am doing a hobby project and I don't know much about engineering; therefore I decided to ask pros. I have a 12v electric device that runs on Car battery only and I need to make it work if there is ...
2
votes
3answers
191 views

Power management for a bus/self powered USB device

I'm building a development board similar to the Arduino, with similar power sequencing requirements. It has both DC and USB power support, and it should prefer DC power. The DC input needs to support ...
3
votes
2answers
180 views

Is it possible to switch relay above the power spec?

I am planning to use a DC drived SPST reed relay. Below I include the spec for voltage, current and power ratings. Contact Rating: 200W Carry Current: 5A Switching Current: 3A Switching Voltage: ...
1
vote
1answer
207 views

P-chan MOSFET as power switch

I want to create a power switch (on/off) for a hot-swap plug-in module that connects to my (future) PCB. Got a MCU on board and a single 3.3V supply, fed from AA batteries with through a DC/DC, this ...
3
votes
3answers
644 views

What is the origin of on and off power switch symbol?

I know I (line) and O (circle) symbols are used to specify a switch that turn on and off the power supply. My question is What is its origin? Because I thought that it represent a power line that ...
2
votes
1answer
424 views

MOSFET on/off switch — asking for critique

I want a "power button" that is actually two buttons; one on, one off. This needs to switch on the order of 15 V and up to 10 A, for a LiFePO4 battery powered device. I don't want to use a hardwired ...
2
votes
2answers
160 views

Simplest way for remote power control?

I don't know much electronics (I'm a software engineer). I want to build or buy a remote power control, controlling over SMS or IP. I don't care if I need to implement my own API or do my own ...
8
votes
3answers
371 views

Blowing a Fuse to Permanently Disable Functionality

Certain electrical designs require permanently disabling hardware functionality on the fly. Sending an overcurrent to a weak fuse may be a method for accomplishing this, breaking the circuit in a ...
2
votes
2answers
528 views

Using a MOSFET as a switch

I would like to use the smallest component to control the power of a component (nano motor). I have seen on the web two main possibilities: DC converter : LTC3127 for example, I change the value of ...
0
votes
0answers
191 views

Help with using mosfets to switch positive and negative supplies

Can any one please direct me to a schematic for a MOSFET based DC switching circuit whose output switches between +100V and -100V. I already came up with the MOSFET driver circuits to switch the ...
1
vote
1answer
227 views

How can I matrix switch multiple lines, including power?

I have devices with several similar boards, all of which are basic computers (with CPU, RAM and ROMs etc.). They all interface to the I/O unit via a standard connector, although the connectors aren't ...
10
votes
4answers
805 views

Why does electric arc in a switch prefer a curved path over a straight path?

Recently I found this video of a 500 kilovolts line being opened under load. When the switch contacts are pulled apart an electric arc predictably starts. While the contacts are close to each other ...
0
votes
1answer
286 views

How could a charger “cut out” when charging is complete? [duplicate]

Possible Duplicate: Why is it so problematic to have close to zero standby power consumption? How would you detect vampire/standby power? This article discusses why cell phone users have ...
4
votes
1answer
364 views

Purchasing a Switch - AC vs DC Current Specifications?

I'm trying to purchase several switches for a DC system with moderately low current (a few amps at 12V). When browsing for switches in parts catalogs (e.g. Mouser and Digikey) there are always ...
1
vote
2answers
334 views

Not use current limiting resistor for switching device on off using TIP122 possible?

I wanting to control MP3 player and amplifier box through PIC board. My project is doing announcement when person standing in near PIC board with proximity sensor. When proximity sensor detecting ...
1
vote
1answer
95 views

High current hot switch capable

I need to design a controller that can switch On and Off a line conducting high currents. the power line: it is supplied by a banks of capacitors the switch: it must close the circuit when a signal is ...
1
vote
4answers
445 views

Selecting 3.3v or 5v to supply EEPROM by µC output

I am looking to select the power supply voltage to an EEPROM depending on the output of a microcontroller. Basically I am building a universal EEPROM (flash) programmer, and I need to select whether ...
3
votes
3answers
2k views

How to make a digitally controlled power switch?

I am new to electronics. I want to make a power switch controller by a digital pin as shown on the following figure. How to do this safely? Update: I forgot to let you know the bulb is just an ...