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Step 5Adding More Lights (and the Maths)
To allow the output transistor to handle more LEDs, start by making sure you have maximum LEDs on each 'string' (ones in series): If your supply is V, then substract 2 and multiply by 0.9 Then, for each White, Blue, Pink or Violet LED, subtract 3; for others (Red, Yellow, Orange, Green) subtract 2, until you get as close to 0 as you can. This is the combination that gives you the most LED for the lowest power wastage.
Each 2N4401 (or BC337) can handle up to 8 'strings' - but you will have to make sure each string is composed of identical LEDs as the first string - then adjust R-bright to 100/n, where n is the number of strings, connected in parallel. The value of R should be 100 * R-bright.
If you have a 9v system, then Start with (V-2)*0.9 = 6.3; Which means we can have 2 Whites OR 3 Reds, And if we have 4 strings of this, then R-bright would be 100/4, or 25-ohms. You can use 22-ohms here, and R should be 22*100, or 2.2k. NOTE: You can have up to 8 string ONLY with the 2 transistors specified. While high-powered devices like the TIP-series will work, they may not have the gain to drive the LEDs fully. If you want to use 2N2222, 2N3906 or similar audio transistors, limit the strings to 4 or less.
One final expansion is to duplicate the entire stage, starting with R, R-bright and the driver Transistor along with the SAME LED arrangement. Connect like the previous Stage, EXCEPT, do not connect R-bright to the input of the op-amp. It is still required but only to make the load identical to the first stage. This way, you can have up to 5 stages in total.
And, if you haven't yet, check out the Next generation of the Musicator! Please vote if you want to see more of the same.
Each 2N4401 (or BC337) can handle up to 8 'strings' - but you will have to make sure each string is composed of identical LEDs as the first string - then adjust R-bright to 100/n, where n is the number of strings, connected in parallel. The value of R should be 100 * R-bright.
If you have a 9v system, then Start with (V-2)*0.9 = 6.3; Which means we can have 2 Whites OR 3 Reds, And if we have 4 strings of this, then R-bright would be 100/4, or 25-ohms. You can use 22-ohms here, and R should be 22*100, or 2.2k. NOTE: You can have up to 8 string ONLY with the 2 transistors specified. While high-powered devices like the TIP-series will work, they may not have the gain to drive the LEDs fully. If you want to use 2N2222, 2N3906 or similar audio transistors, limit the strings to 4 or less.
One final expansion is to duplicate the entire stage, starting with R, R-bright and the driver Transistor along with the SAME LED arrangement. Connect like the previous Stage, EXCEPT, do not connect R-bright to the input of the op-amp. It is still required but only to make the load identical to the first stage. This way, you can have up to 5 stages in total.
And, if you haven't yet, check out the Next generation of the Musicator! Please vote if you want to see more of the same.
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