I have a 7815 fed 30V DC and it puts out 20V, not 15. Other parts do this, not just the first one I tried, so it's obviously something I am doing wrong. I have 2000uF before the regulator and 1000uF after. Is the capacitance too much after the regulator, or can I get away with that and the problem is something else altogether?
I have it feeding a OPA627 and I measured the voltage from the output of the regulator (which is tied to the +v of the opamp), oh, and this also aplies to the 7915, but I am gathering it was the same problem.
The GND pin is indeed connected to ground. And I did think it could have been the lack of loading, but I know not how much I have to load it to work. I don't want to fry my opamp with too much voltage if running it into a load isn't enough to bring down the voltage.
Could a simple resistive load connected across the capacitor after the regulator suffice? For the load from the opamp is going to be rather low. Or once I run the opamp into a load and it draws a little current you think I should be fine?
And I haven't tried to vary the input voltage
The GND pin is indeed connected to ground. And I did think it could have been the lack of loading, but I know not how much I have to load it to work. I don't want to fry my opamp with too much voltage if running it into a load isn't enough to bring down the voltage.
Could a simple resistive load connected across the capacitor after the regulator suffice? For the load from the opamp is going to be rather low. Or once I run the opamp into a load and it draws a little current you think I should be fine?
And I haven't tried to vary the input voltage
Well, this must be the most stupid thread in the history of this forum. I fixed the problem and I am so ashamed of what was causing the problem.
I changed the abttery in my multimeter and now the voltage reads 15V and -15V. Low batteries in my multimeter was the reason for this...
I changed the abttery in my multimeter and now the voltage reads 15V and -15V. Low batteries in my multimeter was the reason for this...
Hi,
At least you have the courage to admit to a silly oversight which is more than...well I'd better shut up...
Cheers,
Well, this must be the most stupid thread in the history of this forum.
At least you have the courage to admit to a silly oversight which is more than...well I'd better shut up...
Cheers,
Not Alone
I have a habbit of needing one part but buying 10 or 20, never hurts to have extra right?
A couple of years ago I purchased (20) 7924 regulators from SAYAL electronics and guess what they all output -18v.
I ran over to radio shack and purchased one 7924 and when I put it in circuit... -24v
Tried to bring the bad 7924s back and was refused a refund or exchange, can't say I blame them but 20 bad regulators...
I have a habbit of needing one part but buying 10 or 20, never hurts to have extra right?
A couple of years ago I purchased (20) 7924 regulators from SAYAL electronics and guess what they all output -18v.
I ran over to radio shack and purchased one 7924 and when I put it in circuit... -24v
Tried to bring the bad 7924s back and was refused a refund or exchange, can't say I blame them but 20 bad regulators...
Nothing to be ashamed ofJoeBob said:Well, this must be the most stupid thread in the history of this forum. I fixed the problem and I am so ashamed of what was causing the problem.
I changed the abttery in my multimeter and now the voltage reads 15V and -15V. Low batteries in my multimeter was the reason for this...
I have mesaured on circuits with the power supply switched off...... happens to all of us.
peranders said:
Nothing to be ashamed of
I have mesaured on circuits with the power supply switched off...... happens to all of us.
I nearly spat my coffee across the room reading this
Reminds me of all the stupid things I've done, including wondering why I have 0v on a componant with the power off!!
Ohhhh no! Look around... there is some pretty stiff competition here. I'll look around for some examples.JoeBob said:Well, this must be the most stupid thread in the history of this forum.
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