Hi!
Or you could use LEDs with built in resistors?
Yours, Mark.
si wrote:
Hi!
Or you could use LEDs with built in resistors?
Yours, Mark.
si wrote:
Yes, generally it works okay for visual brightness and if you are not running very close to the maximum current for the LED type and maximum operating temperature. There's enough internal resistance in most LEDs and the eye's log response is such that the current matching is "close enough" for many purposes.
You guess correctly.
Best regards, Spehro Pefhany
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There's no guarantee the LEDs will share the current equally due to internal differences (even between LEDs of a similar batch). You will at best get one or two at different brightness, at worse one or more LEDs will be totally off. Hence the preference to use the seperate resistors.
Si.
What was the cement mixer? 220v single phase or 208 three phase? Some 220v motors can be reconfigured for 110v, some cannot. If it's a three phase, no way. Replace the motor. Unless you want to get into phase converters and stuff.
to
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I agree that there is no guarantee about the internal characteristics of similar diodes. But then this argument equally holds true for the first diagram - if they all used 300 ohm resistors you couldn't gurantee that they all glowed identically, just the same as if you powered all three through a single 100 ohm resistor.
My answer to the original question is -- Yes that should work and yes the resitor will need to be a third the value of the individual ones in the first diagram. Yes the diodes might differ internally but in my opinion the differences will be small and I doubt that you will notice them. Give it a try.
Cheers,
Nigel
internal
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With different resistors LED characteristic differences are vastly swamped by the series resistance. Under those circumstances the differences in brightness will be minute and most probably not noticeable. I only suggested NO GUARANTEE that the LEDs would share equally in direct parallel it is not impossible, but I have found this so unlikely as to be not worth what is saved in using the extra resistors! As you quite rightly suggest, a R or 1/3rd original value will suffice.
Hey, but what about connecting them in series if you have sufficient supply voltage? Current through the lot is the same and that only takes ONE resistor too!
Si.
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I think he wants to run the mixer on 230 VAC instead of 110 VAC. There's a good chance the motor can be wired either way but you would need to check it wiring instructions.
How large (HP) is the motor? The only other easy, but heavy, alternative is a step-down transformer rated to handle the motor load.
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"Rodney Kelp" writes:
.... and if the voltage is the same as the "rating of the LED" you have a slight problem (eg you can't connect them without a resistor).
Well if the power supply voltage is high enough you can connect the LED in series and use one resistor in series with the lot.
Not a good idea because if the LED are not matched exactly you get a big difference in brightness. They may also age differently - so it may start out ok but in 3 years time one might be brighter than another.
Think about what happens if one LED is 3.59 and the other 3.61V
Colin
Advise sought....
In the early 80's I was able to convert Apple computers (110v US imports) to run on UK mains by swapping the transformer connections.
Can this procedure be used to convert a 110v cement mixer formerly used on a building site ? - hence 110v to comply with regulations.
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Regards,
Neil
Can someone recommend a simple IR remote receiver circuit that can understand about 20 commands.
I am looking for a simple circuit, or a device that I can cannibalize. The outputs are going to drive bi-directional switches.
The IR signals will ultimately be transmitted by a learning remote. I would prefer not to have to build the initial transmitter if I could use a pre-existing remote unless the transmitter circuit is very simple.
Thanks for your help.
Please help me if you can and send me documentation about DECABIT ripple control communication protocol
used in some ripple control receivers.
With through-hole parts (wire leads), the components are inserted on the side which does _not_ have the copper. The procedure you walked through is the way to do it.
If you're a newbie at soldering components, one of the best web resources is the EPE (Everyday Practical Electronics) magazine tutrorial on soldering:
The words "spot soldering" are enough to give one pause. It sounds uncomfortably close to "spot welding". The tutorial will give you what you need to get started without frying your components. If you'd like to look at newbie books, but are a little short on cash, use your local library's resources, including interlibrary loans if available. They have a lot of good resources, too. And look at older issues of electronics magazines for ideas, including EPE (British), Nuts & Volts, and the late Radio-Electronics. Glad to be of help.
Good luck Chris
If IC pins are too large for the holes on the perfboard, you've either got a defective board or the wrong board. For larger semiconductor leads, you might have to solder 22AWG solid wire to the leads to make the board connection. This will be good for an Amp or so of current.
Good luck Chris
Doubtful but possible. Find the electric motor, and look on the nameplate for a wiring diagram. Some AC motors can be wired for either 120VAC or 240VAC. If so, you might want to have an electrician take a look at things before you perform the modification. If there's anything else electrical on the mixer besides a motor, you should also check to see if that will be OK with the mods, too.
Good luck Chris
....
Wrong answer. There is no "proper" value for this resistor, because it's just plain wrong. It _can_ be done, if you want to spend a day or so matching LEDs, but any perturbation in LED current will gave a positive feedback effect, so the LEDs _will_ fail - it's only a matter of time.
Put a resistor in series with each, or with a series string.
Figuring out the resistor value is left as an exercise for the reader. :-)
Cheers! Rich
I have some TLC272s (TI) and TS272s (ST Micro). At first I thought they were just two manufacturer's name for basically the same part, but then I had a closer look at the datasheets, and found that the bandwidth differs. The TS272 gives the gain-bandwidth product as 3.5 MHz, and the TLC272 gives the unity-gain bandwidth as 1.7 MHz (temperature dependent).
Does this mean that there is actually a difference in the parts, or that they were characterized in a different configuration, or that the unity-gain bandwidth is NOT the same as the gain-bandwidth product at some lower frequency, or what?
Thanks for all the help everyone. It was much appreciated. After reading up on open collectors the circuit makes sense and should work great!
-Zinfari
I dont know of a battery operated one but you could get a dog shocker at your local home depot. should work for squirrels too. just a thought.
apple
Thanks
to
aLook at the label for the motor, if it supports 240v you can simply change the connections to run it off that. If it's 120v only (I would think unlikely) then you'd have to replace the motor.
Need battery operated shocker for squirrels. Current should not to be at a level to injure them or other animals. Would be installed on trunk of apple tree. Could the parts from a " one time use " flash camera be used. Thanks
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