Power Redirection?

[Electroenthusiast]

I wanted to design a device; and that requires Continuous Power supply...
So i'm going to use a regulated Voltage Source and a Battery.
The aim is to connect the battery when ever the Power from UPS is OFF.

 

[crutschow]

To avoid charging the battery you will need a diode is series with the battery output. Use a large Schottky type for minimum voltage drop.

 

[Electroenthusiast]

the battery is not rechargeable...
moreover, wont the small reverse current affect the Battery?

 

[crutschow]

If you mean the small reverse current through the diode, no.

 

[Reloadron]

Looking at the image I see a problem / conflict. The output of the UPS (Uninteruptable Power Supply) should be mains power be it 120 VAC at 60 Hz. or 240 VAC at 50 Hz. That feeds a device. However there is a battery in there? I don't get that part?

I wanted to design a device; and that requires Continuous Power supply...
So i'm going to use a regulated Voltage Source and a Battery.
The aim is to connect the battery when ever the Power from UPS is OFF.

What power does the device require?

Ron

 

[Space Varmint]

Why not use a transistor switch? You could have it bias the battery off when the power supply is on and when it drops out the battery would pick up though you would probably have a .6 volt drop with battery supply.

 

[crutschow]

Why not use a transistor switch? You could have it bias the battery off when the power supply is on and when it drops out the battery would pick up though you would probably have a .6 volt drop with battery supply.

0.6V drop is more than a large Schottky rectifier would cause.

 

[Electroenthusiast]

Looking at the image I see a problem / conflict. The output of the UPS (Uninteruptable Power Supply) should be mains power be it 120 VAC at 60 Hz. or 240 VAC at 50 Hz. That feeds a device. However there is a battery in there? I don't get that part?



What power does the device require?

Ron

Heh! there's another circuitry in b/w UPS and device that is nothing but voltage regulator; required 9 V or even less...
Transistor Switch is a good idea... But what if there will no power supply for mili second? will my circuit get reseted??? (IC4060)

 

[Speakerguy]

You could just use a simple switched connector. Many PCB-mount power barrel connectors (made for the type of connectors on wall-warts) have three terminals with one being switched off when a connection to an external power supply is made. You connect your battery to the terminal that gets disconnected when something gets plugged in. This is of course assuming that you will be plugging/unplugging the power source and leaving the battery always connected.

Otherwise, the schottky is the best idea.

 

[Electroenthusiast]

When two Sources are connected in parallel...
How can i know from which source the current is being drawn?
Jus see the 1st Diagram for Idea... I feel it depends on Internal Resistance? AM I RIGHT

 

[Space Varmint]

When two Sources are connected in parallel...
How can i know from which source the current is being drawn?
Jus see the 1st Diagram for Idea... I feel it depends on Internal Resistance? AM I RIGHT

What diagram? You can measure the current by putting the meter in series with either transistor or just check voltage drops across the drain. Shouldn't be hard to figure.

 

[Electroenthusiast]

What diagram? You can measure the current by putting the meter in series with either transistor or just check voltage drops across the drain. Shouldn't be hard to figure.

in this diagram the power suplly from UPS and Battery is shorted ( coneected in parallel ) and is then connected to the Electronic Device; then from which source will the current be drawn?
**broken link removed**

 

[Space Varmint]

in this diagram the power suplly from UPS and Battery is shorted ( coneected in parallel ) and is then connected to the Electronic Device; then from which source will the current be drawn?
**broken link removed**

Why don't you just use a relay? You would attach the power supply to a transistor switch to switch the relay on and off. So you would want to run the battery to the normally closed side and the power supply to the normally open side. Now the power supply will drive the relay on so that it's voltage reaches the load and the battery is disengaged. If the power goes out the power supply will die thereby allowing the relay to drop to it's normally closed contact with is output to the load through the common connection.