Hello, this is very low level stuff but help would be appreciated so I can tell the guy in Maplin he's being an arsehole.

So, I'd like to build a simple circuit to power two flashing LEDs.
I went to Maplin and was told the only way would be to buy two battery packs and power each LED individually. This seemed ridiculous but he did speak with some confidence.

What I was going to do was just buy a 9v battery, wire it to 2 LEDs (the ones with built in resistance) in circuit. then that'd be it. That would do right?

 

You definitely don't need two battery packs. If you have an LED module that is designed to provide a flashing LED when connected to a 9V DC power source, then you are done - just wire two of them in parallel. Depending on what you are doing, you might want some kind of a switch, but maybe connecting/disconnecting the battery is fine.

It sounds like your "Maplin" is a lot like our "Radio Shack" (or at least like it was up until maybe ten years ago, when they gave up most of any pretence of being anything but a place to buy consumer electronics). I always got a laugh out of their slogan: "You have questions. We have answers." It seemed, somehow, incomplete without being followed by, "Most of them are wrong, but we have them."

 

Brilliant, thanks very much. I suppose it's too much to hope that anybody would hire staff that new what they were talking about.

Thanks again.

 

For the most part, yes, it's hoping for too much. It's a shame that it's that way, but it is.

There was a store here for a while called "Tech America" that was actually owned by Radio Shack. Essentially, it was an modern day version of what Radio Shack stores were back when they first started, which was a place for Ham Radio guys to go and most of the clerks were themselves ham operators and were working at Radio Shack in order to get the employee discount. Tech America specialized in component sales for people that wanted to build up their own computers and such and the first time I went there I was amazed by how lknowledgeable the people working there were -- and they had a huge technical books selection that was to die for. But everytime I went there (which was every few months because it was nearly 100 miles away) the staff was increasingly replaced with off-the-streat hires with zero technical knowledge and the book section kept getting smaller and smaller and was eventually just a magazine rack at the time I threw up my hands and never went back. They went out of business shortly thereafter. Gee, I wonder why! Now, in fairness, it could well be that they would have gone out of business sooner had they kept the knowledgeable staff and the excellent book section and other things because those things cost more money and you can't operate in the red indefinitely (even if you're the government, but try telling them that). Thus, cutting back may simply have reflected what had to be done in order to have a shot at staying in business, in which case they were doomed from the start.

 

It's sad that they didn't know about this kit and the many versions of Blinky that are out there. My kids made these in grade school.

 

That's why I just joined the forum - nobody in the "professional" world seems to know anything anymore. My professor is "learning" VHDL with us! How is she supposed to teach what she doesn't know?
The "job creators" don't want employees with knowledge...they take the government tax breaks (but don't want he government to tax to get money to give those breaks) if they're in the red; then fold.
Radio Shack hires kids in high school for minimum wage part-time to avoid paying benefits and college MANAGEMENT (not electronics) graduates to run the stores.

Any way, pardon the rant; the LED problem is simple enough...like WBahn said, you can wire them in parallel to a single battery if they are made for 9V. If they're 2V (or another value) you can put them in series with a resistor to drop the remaining voltage.

 

No, you cannot wire them in series.

 

That's why I just joined the forum - nobody in the "professional" world seems to know anything anymore. My professor is "learning" VHDL with us! How is she supposed to teach what she doesn't know?

If she's got strong fundamentals, then she may well be able to do it just fine. I have been in the situation several times of having to teach material that was new to me and it was very challenging because I had to make sure that I stayed one step ahead of the students. But one thing it also did was make me very aware of many of the struggles that the students were going to face because I was facing them too. The difference was that I had enough depth and breadth of background that I could work my way through them whereas they were pretty high walls for many of the students, so I was able to give a lot more and better hints and guidance.

the LED problem is simple enough...like WBahn said, you can wire them in parallel to a single battery if they are made for 9V. If they're 2V (or another value) you can put them in series with a resistor to drop the remaining voltage.

You almost certainly can't wire them in series. Remember, the OP is not talking about LEDs, he is talking about flashing LED modules. That would be like saying that you can take two TVs intended for 110V and put them in series in order to run them off 220V.

 

I am teaching MSP430 fundamentals to students even though this is new to me.
But as WBahn says, I stay one step ahead of the students.
In fact, I am a hundred steps ahead of students because I am no stranger to MCUs and have worked with dozens of other ones. Learning another one is just another stepping stone and learning another one is easier than all of the previous ones.

 

RadioShack stores in Canada began to sell cell phones and kids toys. Also a few computer accessories. Their staff and spec's did not know anything about electronics.
They were sold to Circuit City of US and called THE SOURCE but they also did poorly.
Now THE SOURCE is owned by BELL CANADA where they sell cell phones and kids toys.

 

I went into THE SOURCE to find a stereo to mono 3.5mm adapter or the parts to make my own.

After I had a long search, the sales associate came over and I told him what I was looking for.
He promptly pointed out to me that the items on the rack in front of me were for mono and the items on the left rack were for stereo. I politely said thanks.

Then I told him exactly what I was looking for, what the two ends should look like.
Then he apologized and said he knew nothing about electronic components. WTF?

 

I went into THE SOURCE to find a stereo to mono 3.5mm adapter or the parts to make my own.

After I had a long search, the sales associate came over and I told him what I was looking for.
He promptly pointed out to me that the items on the rack in front of me were for mono and the items on the left rack were for stereo. I politely said thanks.

Then I told him exactly what I was looking for, what the two ends should look like.
Then he apologized and said he knew nothing about electronic components. WTF?

Did he try to sell you a cell phone?

 

I went into THE SOURCE to find a stereo to mono 3.5mm adapter or the parts to make my own.

After I had a long search, the sales associate came over and I told him what I was looking for.
He promptly pointed out to me that the items on the rack in front of me were for mono and the items on the left rack were for stereo. I politely said thanks.

Then I told him exactly what I was looking for, what the two ends should look like.
Then he apologized and said he knew nothing about electronic components. WTF?

Just further evidence that civilization is a self-defeating concept.

 

A salesman at THE SOURCE sells cell phones and kids toys and knows nothing about electronics.
Some of their "RadioShack" parts have been there for years and they also had no spec's.

Maybe HOME DEPOT has what you want.