Your 'thick' 0V link in the centre is OK, I did notice it after I had posted, so I posted the edit.
You have made decent layout in quick time, that layout program is nice and simple to use.
Consider the LED drain on the 9Vbty.
Any recommendations/tips for cutting the veroboard to size?
Use an special soldering iron cutting tip ??
A saw?
Stanely knife?
I haven't seen the original blue epoxy-fiberglass Veroboard for years.
The original epoxy-fiberglass Veroboard was a dark blue colour. The sheets were about 50cm long and about 10cm wide (34 strips).
I looked for a pic in Google Images but couldn't find one.
I am trying to reduce the 9V battery to 2.2 to allow a 2.2VDC LED to work.
I came up with whats in the diagram. This is giving me 2 VDC when measured on my DMM however when I attach my LED it does not work.
Any ideas as to why?
Or is there a better solution to do this (maybe one resistor)?
Thanks
I am trying to reduce the 9V battery to 2.2 to allow a 2.2VDC LED to work.
I came up with whats in the diagram. This is giving me 2 VDC when measured on my DMM however when I attach my LED it does not work.
Any ideas as to why?
Or is there a better solution to do this (maybe one resistor)?
Thanks
Hi,
I did query this LED.
Consider you have an LED with a 2Vdp and you want to run it from a 9Vdc supply.
This means you must drop 7V in a series resistor.
You say you want 20mA thru the diode [ I would suggest thats to high for a 9Vbty]
anyway Rseries = 7V/0.02 = 350R say 390R
For 10mA Rs = 7/0.01 = 700R say 680R
Do you follow OK?
EDIT: You only need one resistor.
If you must have a 20mA LED [wasteful for the battery] the use a 390R
Thanks Eric,
I am using a push button, with an LED, I know it might be an additional drain on the battery, but I am not too worried about this for now, I may not need the switch nor the LED later on.
Here is the datasheer for the LED:
Page 435.
https://www.electro-tech-online.com/custompdfs/2008/11/0900766b8002e7a6-1.pdf
And one thing that I am surprised about is that when I use my DMM is show about 8.23 VDC, and that when I use a 390 OHM resistor.
I intially used a similar method to workout the resistor size needed but when testing did not show 2VDC I thought I was doing something wrong.
hi,
Looking at the datasheet for the PB it states it has a inbuilt resistor for the LED.!
No external resistor required.
Did you get 12V version of the P/B?
I tried both the 390R and 680R and both seem to work. I am thinking that the 680R is better to use but I do not know which one will put more strain on the battery though.
hi,
Use Ohms Law to answer that problem: Icurrent = Volts/Resistance
So 9Vbty - 2.2Vdp = 6.8V [ to drop across the resistor]
Gives:
I1 = 6.8/390R = 17.4mA
I2 = 6.8/680R = 10mA..
If the battery was only driving the LED, with a 680R it would last twice as long compared to a 390R.
I would have thought the LED would be bright enough at 10mA.
hi,By the do you recommend using single or multicore cable connectors for the Veroboard? I was thinking of using the phone cables that are single core but the color does not help, I do have multicolored multicore cable but I am reluctant to use it becuase it is normally used for audio (I think). So I ordered single core cable but until it arrives I am twiddling my thumbs
Your vision's response to brightness is logarithmic to allow you to see a wide range from the light from a candle to sunlight. Therefore an LED's brightness does not look much different when its current is halved or doubled.
Your 9V battery measures "only" 8.23V when it is loaded because it is running down.
A 9V battery doen't have much power. Look at its datasheet from the website of a battery manufacturer like Energizer:
1) It is 9.0V when new.
2) With a 27mA load its voltage drops to 8V in about 1 hour.
3) Its voltage drops to 7V in about 7 hours but then the current is less.
4) Its voltage drops to 6V in 22 hours but then the current is very low.
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