Sorry the photo is upside down The meter read 0.05vdc so .05/1= .05A so each light pulls .05A and if there are two of these lights on each channel then i need to produce .1A per output channel on the 4017. Will my schematic still work?

 

Cheap ******* LED marker lights like that are also sold in Canada.
But they are illegal to be used on streets because they are too dim and have a viewing angle that is too narrow.
The law should make their importing and sales illegal.

 

Haha they say right on it DOT approved.... (Department of transportation) They were $8 a piece they are completely waterproof they are pretty bright with the 1ohm resistor.... do you think My Schematic will amplify the current enough? i need to order the parts if you think it will work

 

The 4017 can only source about 18mA on a good day with a tailwind down a steep hill, but if you use the suggested modification on each channel, you'll be able to source about 300mA per 4017 output. You could have up to three of your marker lights per output with the addition of the driver circuit I posted.

 

Thanks Guys!!!! Ill build it up and let you know how it goes!!!! should i use 1/2 or 1/4 watt resistors?

 

You should calculate the wattage requirement yourself.

P=EI (voltage x current)
P=I^2R (current squared x resistance
P=E^2/R (voltage squared / resistance)
Double the result you get, and select a wattage that is equal to or higher than that doubled result.

 

Hey thanks guys i really apreciate all the help! i have the parts on order and once they get here ill let you know how it turns out! Is there a different NPN Darlington transistor i could use besids the MPSA14? i have them on order but im impatient. My school has a huge electronics Storage Room that has alot of components but i cant find the MPSA14's in it.

 

If you can find ULN2004A or ULN2804A IC's, each one of those has seven or eight Darlington pairs in them; and they already have 10k base resistors.

2N6426/2N6427 could substitute for the MPSA14.

Trying to give a complete list would take quite a while. What transistors do they have on hand?

This link will do a search on Mouser for NPN Darlingtons in a TO-92 package:
http://www.mouser.com/Search/Refine.aspx?Keyword=NPN+Darlington+TO-92

 

In Your Schematic you gave me How did you figure out the values of the Resistors? just for future reference...

 

Thanks i think they have some of the 2N6426's we will see if they have enough of them if not ill just wait thanks bro!

 

4000-series CMOS has a pretty low current source capability. You can get more than 6mA out of them, but you start stressing the IC.

That's why a Darlington was suggested in the first place; the transistor configuration results in the gain of the two transistors being multiplied.

The 2N2907A can source up to around 300mA before it starts getting warm; it's actually rated for up to 500mA, but best to use it well below that.

When using a transistor as a saturated switch, you need for the base current (Ib) to be around 1/10 the desired collector current (Ic). You also need to figure in the base-emitter voltage drop (Vbe). Vbe will vary somewhat from transistor to transistor, but it's more dependent on how much current is flowing to the base. For your purpose, assuming 0.8v will be in the ballpark.

So, the problem is to figure out first what base current you will need to drive the 2N2907A transistor to source up to around 500mA or so. The basic formula for that is:
Rb=(Vcc-Vbe) / (Ic/10)

Your supply is roughly 12v. There's another item to consider, and that's the Vce (voltage from the collector to emitter) of the MPSA14 Darlington in the diagram. That'll be in the vicinity of 0.8v as well
Rb=(12v-(0.8v+0.8v)/(500mA/10)
Rb=10.4/0.05
Rb=208 Ohms

208 Ohms isn't a standard value, and you also have to consider the "what if" game when your alternator is charging.
Now your voltage will be different when the alternator is putting out current; perhaps 14v.
Rb=(14v-(0.8v+0.8v)/(500mA/10)
Rb=(14-1.6)/0.05
Rb=12.4/.05
Rb=248 Ohms
That's not a standard value either. 220 Ohms is a standard value in between 208 and 240 Ohms.

Calculate wattage: 12.4*.05 = .7; double for reliability and you get 1.4 Watts. Whoops, that's a bit much.

Let's scale the base current back a bit. 300mA should be more than enough to supply your lights, and assume Vcc will be nominally 13v.
Rb=(13v-(0.8v+0.8v)/(300mA/10)
Rb=(13-1.6)/0.03
Rb=11.4/.03
Rb=380 Ohms.
Not a standard value. 360 and 390 are standard values. Let's go with 390, and check against the 12v and 14v partial results I got before.

12.4/390=31.8mA
10.4/390=26.7mA
Both are in the ballpark.
12.4 * 31.8mA *2 = .788mW ; you'll still need 1W resistors, but power use will be less, and they'll still work.

 

Wow thats alot of information! thank you So i need to find 1.5watt or 1watt 220Ohm Resistors? can i use 1/2 watt? Or can i change something to make it less than 1watt because i already ordered the parts....?

 

sorry 390 or 220ohm resistors

 

So i found online 2watt 220ohm resistors should i go ahead and get those? and then upgrade the other resistors to 1watt?

 

So i went to the Component closet at school and found some 200Ohm 2watt resistors and some 220Ohm 1 watt 10 of each will they work? its 15$ to buy them online so if i can use these i really would like to..

 

Gee, I already showed you how to do the calculations. Why don't you try doing the calculations using the 220 Ohm 1 Watt and 200 Ohm 2 Watt, and see what you come up with?

It's for your benefit; if you try working through the math, you will know how to do it yourself in the future. You DID say you wanted to know how to calculate them, right?

 

Ha ha yes your right But according to your calculations you provided me then i need 2watt ones but 1watt ones will work but will become warm... If i dont double it then i should be fine... so ill use the ones i found thanks for your help!

 

So i put it together exactly as your diagram says and it just keeps the lights on Full all the time? It doesnt turn off or anything but glow brightly?

 

Here is the schematic exactly as i have it wired up... Whats wrong?

 

I have been doing some research into basic amplifying circuits and alot of them have a Capacitor and a diode to dissipate extra voltage in the circuit. Should i be doing that here? Also can i test anything with my Multimeter to see if i have something hooked up wrong? Thanks for all your help i am so close!!! i can feel it just a little tweeking and i should be there!