resistance values for LED's

The big resistor is a surface mount. It mounts to the surface of a panel.

 

Heat sink

Fanie,

The panel acts as a heat sink to dissipate the heat generated by the resistor.

Rx

 

Nmemomic Assistance

Some people find nmemonic phrases useful, so I present two for your color coding pleasure. Just look at the chart above and recite the phrase and you will see how it is used.

The British version:

"Build Better Resistors Or Your Grid Bias Voltage Goes West!" Mas will remember what a bias voltage is, but I bet the youngsters here won't have a clue.

And a much easier one to remember, albeit not exactly "Politically Correct," taught to me at a Navy Service School in 1961:

"Bad Boys **** Our Young Girls, But Violet Gives Willingly. Get Some Now!" The last three codes refering to the tolerance of the resistor (Gold, Silver, No-color).

That last one has served me well for 48 years now.

BillyDoc

 

RXComp, I'm pulling your leg. You should read the previous posts...

I do have such a resistor tho. I stripped it out of a motor start panel, and use it for testing audio amps or other things in need of a dummy load.

I must say, since smd components I haven't used the resistor / capacitor colour coding in ages. I guess it's like morse, once you know it and worked with it you don't forget it easily. The old witch assembles our stuff, so I handle components sparsely off late.



As for the LED dimmer, it works well. You can switch on / off or dim anywhere in between. The off current is currently (pun) 0.7mA which is too high for my liking, I will drop it even more. Batteries mustn't know it is still there even if you have a horde of these connected.

The 317 current regulator input to output voltage drop is higher than I anticipated . I have two LED's in series on a board instead of three. It however is easy to parallel boards, and there can then be 2, 4, 6, 8 etc LED's.

The spectrum analiser (Billy) is locked into a safe and the safe's owner 'forgot' the code after my friend's son played with the combination key I will make another plan to meaure if there are any emission levels.

The switching signals however looks as expected on a scope. I very much doubt it if there will be any emissions, if there are it would be minute and would without any doubt have no effect on any equipment. PWM switching at 500Hz.

 

Resistor

Yes, you got me there. Looking at your posts, you are well informed.

 

Not really, the technology changes so fast it's a full time job just trying to keep up, which is why most people specialize in one particular direction.