Question about wiring from a power supply

In summary: Bhttp://cgi.ebay.com/HP-6236B-Triple-Output-Power-Supply,-with-manual_W0QQitemZ170309876636QQcmdZViewItemIn summary, the conversation discusses the use of a power supply for a circuit that requires a voltage value of -5V. The individual asks if they can simply connect a wire from the (-) terminal of the power supply to the Vt and if they need to wire the ground terminal of the power supply somewhere. It is then explained that the power supply has floating outputs and can be treated as separate batteries. The conversation also covers using a fixed
  • #1
atlbraves49
81
0
I'm considering using this power supply:
http://salestores.com/pr30trouposu2.html

now.. if i wanted to get a voltage value of -5V into a circuit (such as http://www.tekscan.com/images/flexi-circuit-new.jpg" ), could i just put a wire from the (-) terminal of the power supply, to the Vt? And then what.. would i need the ground terminal of the power supply wired somewhere, and if so.. where?

Thanks
 
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  • #2
atlbraves49 said:
I'm considering using this power supply:
http://salestores.com/pr30trouposu2.html

now.. if i wanted to get a voltage value of -5V into a circuit (such as http://www.tekscan.com/images/flexi-circuit-new.jpg" ), could i just put a wire from the (-) terminal of the power supply, to the Vt? And then what.. would i need the ground terminal of the power supply wired somewhere, and if so.. where?

Thanks

Yes, these sorts of power supplies normally have floating outputs, and you can treat them as if each side was a separate battery. The green ground terminal is connected to the chassis ground which is connected to your local Earth ground (so, in undergraduate labs, it's not employed more frequently than it is).

If you were looking to generate, say, +/- 9 V (to power something like an Op-Amp) you would set both sides to (positive) 12, and then connect the negative terminal of one side to the positive terminal of the other side, using this node as your circuit ground (which you may, or may not, connect with another jumper or the metal clip thingie that's on the banana plugs).

The easier way of doing the above (without the jumpers) is to press the 'Series' button which (internally) does the same.

Note that the (fixed) 5V supply may or may not be connected to Earth ground, and in any case, doesn't offer any current limiting!

EDIT: You can use the (fixed) 5V supply in a similar fashion to the above, thus using all $300-$500 worth of your bench power supply!
 
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  • #3
my idea for using this power supply with the above circuit was as follows:

For the left supply (set to 5V):
(-) terminal to the -5 Vt
(+) unused
(Ground) to the ground of the circuit

For the right supply (set to 9V):
(-) terminal to the -9V of the op-amp
(+) terminal to the +9V of the op-amp
(Ground) to the ground of the circuit


Would that work?
(note that the fixed 5V wouldn't be used)
 
  • #4
atlbraves49 said:
my idea for using this power supply with the above circuit was as follows:

For the left supply (set to 5V):
(-) terminal to the -5 Vt
(+) unused
(Ground) to the ground of the circuit

For the right supply (set to 9V):
(-) terminal to the -9V of the op-amp
(+) terminal to the +9V of the op-amp
(Ground) to the ground of the circuitWould that work?
(note that the fixed 5V wouldn't be used)

This wouldn't work. As I mentioned in the previous post, the ground terminal isn't connected to anything! Note that when they say +/- 9V, they mean that you need 18V across the two terminals, tapped in the middle to give you a ground point. Reread the previous post, and then do the following:

1) Put the power supply into series mode
2) Set both sides to 9V
3) Use the positive terminal of the left supply as +9, the negative terminal of the right supply as -9, and either of the other two terminals as ground. DO NOT USE THE 'GROUND' TERMINAL AS GROUND!
4) Connect the positive terminal of the 5V fixed to either of the terminals in 3, and the negative terminal as your -5V supply.

EDIT: And then verify the voltages, relative to the negative terminal of the left or positive terminal of the right using your DMM.
 
  • #5
alright i tested and got it figured out for the above example, but the power supply we have to use doesn't have a negative terminal for the "6V supply". It has the 6V (+), the +/-25V, and the COM. I can set the 6V supply to 5V, and if i inverse the multimeter leads, it will read it as -5V, but how do i get it to actually supply -5v to the circuit? Wont it actually be supplying the +5V?
 
  • #6
atlbraves49 said:
alright i tested and got it figured out for the above example, but the power supply we have to use doesn't have a negative terminal for the "6V supply". It has the 6V (+), the +/-25V, and the COM. I can set the 6V supply to 5V, and if i inverse the multimeter leads, it will read it as -5V, but how do i get it to actually supply -5v to the circuit? Wont it actually be supplying the +5V?

EDIT: I reread your post, and it appears I was attempting to answer the wrong question. Is this power supply not the one you linked to above? If, as you say, there are a grand total of 4 terminals (+/-25V, +5V, COM) then you're probably stuck, as you don't have independent outputs. I'd ask your lab instructor if you can get a better triple output power supply with independent outputs.
 
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  • #7
MATLABdude said:
EDIT: I reread your post, and it appears I was attempting to answer the wrong question. Is this power supply not the one you linked to above? If, as you say, there are a grand total of 4 terminals (+/-25V, +5V, COM) then you're probably stuck, as you don't have independent outputs. I'd ask your lab instructor if you can get a better triple output power supply with independent outputs.

here is the power supply we were allowed to borrow:

hp 6236B

http://cgi.ebay.com/HP-6236B-Triple-Output-Power-Supply,-with-manual_W0QQitemZ170309876636QQcmdZViewItem


so we can't get -5V from this?

if not, i guess I am back to needing to buy this:
http://salestores.com/pr30trouposu2.html

unless someone knows a cheaper alternative to get -9V, 9V, and -5V
 
  • #8
If you have an old ATX power supply, the following may be of use to you:
http://www.techpowerup.com/articles/other/22

ATX v2.0 connector pin-outs:
http://en.wikipedia.org/wiki/Atx#ATX12V_2.0

Be careful... These things often don't have great output regulation, stability, or nice features like current limit / short circuit protection. What do you expect for something that costs $20-$50? You could try using a 7809 and/or 7909 to regulate the +/-12V down to +/-9V with a little better regulation.

For future reference, please refrain from PMing people that you've updated a thread; most people don't have PM notification, but DO get notified whenever a thread they're subscribed to gets a new post. That and we can see something's floated up to the top of the page again.

EDIT: Before you start hacking, make sure the sticker on top of the power supply says that there is a -5V output. You could also just use a 7905 on the -12V rail to regulate this down to -5V instead.

Also, how to convert a computer ATX power supply to a bench power supply:
http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply
 
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  • #9
so according to my professor, the power supply without the negative terminal for the +6V output CAN still give -5V instead of just +5V...

Sadly he wouldn't tell me how...

he said "if I showed you with a meter on my desk - it can be done on the bench."

(when you use a multimeter and reverse the leads, it shows -5V)

so any ideas?

again, this is what it looks like:
http://www.eqrentals.com/sale/details/HTE0506.html
 
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  • #10
atlbraves49 said:
so according to my professor, the power supply without the negative terminal for the +6V output CAN still give -5V instead of just +5V...

Sadly he wouldn't tell me how...

he said "if I showed you with a meter on my desk - it can be done on the bench."

(when you use a multimeter and reverse the leads, it shows -5V)

so any ideas?

again, this is what it looks like:
http://www.eqrentals.com/sale/details/HTE0506.html

Well, you can, if that's all you wanted. You can't if you want +/- 9V, since all of these outputs share a common ground, and a common banana jack. Now, if you happen to have another power supply with which to supply +/-9V, you could use this one for a dedicated -5V supply.
 
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1. How do I know which wires to use from a power supply?

When wiring from a power supply, it is important to first identify the positive and negative terminals. The positive terminal is typically labeled with a "+", while the negative terminal is labeled with a "-". Make sure to use wires that are rated for the appropriate voltage and current for your specific power supply.

2. Can I use any type of wire for wiring from a power supply?

No, it is important to use wires that are specifically rated for use with electrical equipment. This ensures that the wires can handle the voltage and current from the power supply without overheating or causing damage.

3. How do I connect multiple devices to one power supply?

You can use a power strip or a splitter to connect multiple devices to one power supply. Make sure to calculate the total current draw of all the devices and ensure that the power supply can handle the load.

4. What is the proper way to strip and connect wires from a power supply?

To strip wires, use wire strippers to remove the insulation from the end of the wire. Then, twist the exposed wire strands together and secure with wire connectors. It is important to ensure that there are no loose strands or exposed wires to prevent any potential hazards.

5. Can I extend the wires from my power supply?

Yes, you can extend the wires from your power supply using wire connectors or soldering. However, be sure to use wires that are of the same gauge and rated for the same voltage and current as the original wires to avoid any potential issues.

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