Can a common 9V power supply be used as a -9V supply?

In summary, it is safe to use a transformer-isolated power supply as a minus supply, as long as it does not have a 3-pin power plug. However, it is important to note that turning on the plus and minus supplies in an asymmetrical manner may cause damage to certain circuits. The suggested 9-V unit may have a low current limit, so it may be beneficial to look for a higher current limit unit for a slightly higher price.
  • #1
atlbraves49
81
0
So if you have something like this:
https://www.amazon.com/dp/B0002H07CW/?tag=pfamazon01-20

can you use it as a -9V supply?

My circuit requires a +9V and a -9V supply, and since I am having issues finding fixed +/-9V supplies, i was wondering if i could just use a 9V supply for the +9V, and another 9V supply as the negative?And then could the same be done with a 5V power supply like this:
https://www.amazon.com/dp/B001KU44HE/?tag=pfamazon01-20

to get a -5V supply?
 
Engineering news on Phys.org
  • #2
atlbraves49 said:
So if you have something like this:
https://www.amazon.com/dp/B0002H07CW/?tag=pfamazon01-20

can you use it as a -9V supply?

My circuit requires a +9V and a -9V supply, and since I am having issues finding fixed +/-9V supplies, i was wondering if i could just use a 9V supply for the +9V, and another 9V supply as the negative?


And then could the same be done with a 5V power supply like this:
https://www.amazon.com/dp/B001KU44HE/?tag=pfamazon01-20

to get a -5V supply?

Yes, those are transformer-isolated power supplies, so you can stack them to make split supplies.
 
  • #3
It is perfectly safe to use one as a minus supply if the unit does not have a 3-pin power plug. I have found that some units have a 3-pin power plug with the ground connected to the outside shell of the dc power connector. One problem you will have (besides isolating the shell of the neg supply plug) is that unless you switch the common AC power, you will be turning on the plus power before or after you turn on the minus power. This assymetric power application can sometimes damage circuits (like when the minus supply provides bias to bases on discrete transistors). The 9-V unit you are looking at has a wimpy (100 mA) current limit. You can probably find 1 amp plug-in units for a few $ more.
 

1. Can a 9V power supply be used as a -9V supply?

No, a 9V power supply cannot be used as a -9V supply. The polarity of a -9V supply is reversed compared to a 9V supply.

2. Is it safe to use a 9V power supply as a -9V supply?

No, it is not safe to use a 9V power supply as a -9V supply. The voltage and polarity are different and can cause damage to the circuit or device.

3. How can I convert a 9V power supply to a -9V supply?

To convert a 9V power supply to a -9V supply, you would need to use a voltage inverter or a switching power supply. These devices can change the polarity and voltage of the power supply to match the requirements of a -9V supply.

4. What are the risks of using a 9V power supply as a -9V supply?

The risks of using a 9V power supply as a -9V supply include damaging the circuit or device, as well as potentially causing electric shock or fire hazards. It is always best to use the correct power supply for the intended purpose.

5. Are there any alternatives to using a -9V supply?

Yes, there are alternatives to using a -9V supply. Some circuits or devices may be able to function with a different voltage supply, such as a 5V or 12V supply. If a -9V supply is required, using a voltage inverter or switching power supply is the safest and most reliable option.

Similar threads

Replies
19
Views
1K
  • Electrical Engineering
Replies
9
Views
1K
  • Electrical Engineering
Replies
33
Views
2K
Replies
7
Views
1K
Replies
3
Views
1K
  • Electrical Engineering
Replies
8
Views
2K
  • Electrical Engineering
2
Replies
36
Views
2K
  • Electrical Engineering
Replies
17
Views
3K
Replies
61
Views
6K
Replies
13
Views
1K
Back
Top