Wall adapter - says 9v dc but measures at 17v

[Reloadron]

You should post a new thread. Your question has changed from "why cheap wall warts change voltage" to "how to design a 3 volt regulator".

You are kind.

Also my bad as I thought he wanted to drop 3 more volts and not get 3 volts. After reading the entire thread my head hurts.

Back in the beginning:

However, pluged it in and measured it with a multimeter. The meter said that the voltage was 17v.

Is this normal? I was hoping to add a wall adapter socket to a DIY-synth-keyboard-thing. I was going to base a lot of the design on it being 9 volts.

Ron

 

[redepoch7]

You are kind.

Also my bad as I thought he wanted to drop 3 more volts and not get 3 volts. After reading the entire thread my head hurts.

Back in the beginning:


Ron

Just prior to the posting from bychon about changing to a new thread I was thinking about how this conversation had drifted from the original post. Thus, I haven't posted since. However, I feel I need to add one final thing.

I'm not exactly sure how your last posts helps the conversation at all.

Yes, it's true that I don't know as much as these great folks who have been helping me out. But rest assure that I did take a lot from the conversation and learned a great deal. I'm teaching myself about electronics and trying to have fun at the same time. I'm sorry if this conversation makes your head hurt... don't read it then.

Hopefully, someone as inexperienced as myself will be able to learn something from this thread and won't have to ask as many "head hurting" questions as I did.

Thank you, Reloadron, for the "positive" remarks. It's that wonderful sense of community and benevolence what keeps me coming back to this forum and recommending it to others.

Sincerely,
Nick

p.s. I did read the article about wall warts and I did google wall warts. A lot of the information is a little over my head at this point so I wasn't able to take as much from it as one would have hoped. But I'll keep reading and trying to understand it all and hopefully I won't have to ask any more questions.

 

[Reloadron]

Nick

p.s. I did read the article about wall warts and I did google wall warts. A lot of the information is a little over my head at this point so I wasn't able to take as much from it as one would have hoped. But I'll keep reading and trying to understand it all and hopefully I won't have to ask any more questions.

You have questions, you ask them and never hesitate. Long before any formal education in electronics I relied on asking my father who would frequently just hand me a book. Sometimes and don't I know it, answering questions can be as frustrating as asking them in a forum like this. It's like if you don't really understand what the person is asking you are sitting in front of a screen, eyes closed trying to imagine where they are going with the question and what they want to know. Sometimes the person answering has no clue as to the technical level of the person asking and that makes for real difficult. You babble a bunch of technical jargon and the poor person asking hasn't a clue what you said.

I think the bottom line is simply that if you Google something like a wall wart and don't understand what you have read then ask questions in here. Also if throughout this thread I said or did anything out of line I am sorry. I would never want to think my attitude on a bad day dissuaded someones learning.

Ron

 

[arunb]

what voltage is the keyboard rated for ?? also how much current does it draw ??

 

[Hero999]

First, I did connect it across the power rails. I did this because I asked if I should and someone told me (in this post) that that was how to do it.

Well I'm not going to go back and read through the whole thread.

It is possible that the person who said that made a mistake but it's more likely that they were telling you how to measure voltage, not current.

To measure voltage, you connect the meter across the power supply rails.

I will always measure in series from now on... thanks for the heads up.

That's right, for current, you need to put the meter in series with the device you're measuring the current consumption of.

Putting the meter in parallel will measure the short circuit current which will be very high and has probably blown the meter's fuse. You can test this by setting the meter to measure current and connecting the probes to another meter set to measure resistance. The Ohmmeter should measure near 0, if the fuse is good, otherwise it will be open circuit, indicating that the fuse is bad.

If you don't have another meter, you can remove the fuse from the meter and test it with the same meter set to resistance.

If the fuse is blown, you'll need to replace it with one of not only the same current rating but the same type. It's important to use the right kind of fuse, otherwise your meter won't be properly protected, if you're not sure, check the manual.