Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

[SOLVED] Switch between two equal-voltage terminals?

Status
Not open for further replies.

bobsun

Full Member level 2
Joined
Mar 5, 2011
Messages
120
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,296
Activity points
2,239
Hello,

I would like to ask a question on switch.

It’s not difficult to make a switch from high voltage to low, such as turning on and off a motor, using a transistor. However, if the purpose is to cut a connection between two “high” voltages, how could that be achieved?

switch_High_High.png

In the attached image above, there is a 5V battery and a capacitor and a resistor. If the switch is connected on, the capacitor will get charged; if it is off, the battery voltage and capacitor voltage would be separated.

If I would like to control the manner how battery charges the capacitor, then it requires that the connection between the positive end of the battery and the upper end of the capacitor be controlled. Transistors could works for switching paths from high to low, but for things like here between two terminals with same or similar voltage level, it seems that transistor cannot do the job. Then how can it be done?

I know using reed could possibly achieve that; but is that reliable for possible millions of switches? Is there any other component to do this?


Bob
 

FvM

Super Moderator
Staff member
Joined
Jan 22, 2008
Messages
50,075
Helped
14,507
Reputation
29,284
Reaction score
13,452
Trophy points
1,393
Location
Bochum, Germany
Activity points
287,661
Single MOSFET or bipolar transistor sare restrcited to switch unipolar voltages. As long as the voltage difference between the switched terminal has always the same sign, transistors can work well. If the voltage difference can have both polarities, two transistors can be combined. This is most simple with MOSFET, that can be connected back-to-back. See a photovoltaic solid state relay as an example of a bidirectional switch: http://www.irf.com/product-info/datasheets/data/pvg612a.pdf
 
  • Like
Reactions: bobsun

    bobsun

    Points: 2
    Helpful Answer Positive Rating

bobsun

Full Member level 2
Joined
Mar 5, 2011
Messages
120
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,296
Activity points
2,239
FvM,

Thanks for the answer. I am reading the linked PDF.

Bob
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top