User:Chotee/NoFeedback-ManagementIntervention

1mx1m screen of RGB lights that slowly and independently change colour. All patterns are just your mind playing tricks on you.

Parts

• [Ordered] LEDs - https://nl.aliexpress.com/item/free-shipping-500pcs-5mm-Straw-Hat-Colorful-Slow-Flashing-Flash-RGB-Red-Blue-Green-LED-Leds/32231092414.html
• 11 x duct (11*€3.19) https://www.gamma.nl/assortiment/kabelgoot-kunststof-wit-20x10-mm/p/B651828
• 10 Bouten M5x80mm €8 - https://www.gamma.nl/assortiment/gamma-slotbout-m6x80-mm-verzinkt-20-stuks/p/B458213
• 1000x1000mm Plexiglas - €23 - https://www.gamma.nl/assortiment/martens-acrylplaat-transparant-100x100-cm/p/B151681
• 2 x 1m 5mm staal/hout

Electronics

• 500 Slow color changing RGB leds.
  • max led forward current is 20mA.
  • RGBs forward-voltage oscillates between 3.2v and 3.8v (±15%)
  • LEDs max continious current at 20mA.
• 22x22 leds (484) [sqrt(500) = 22.36..]
• Powered by 12v PC PSU or 20v LT power-brick.

12v

• 12v/3.8 (V-max-led-forward) = 3.15 LEDs; 3 LEDs in a chain.
• There are 161+1/3 chains [484/3]
• Vmax = 3 * 3.8Vf = 11.4v; 0.6v left.
• Vmin = 3 * 3.2Vf = 9.6v; 2.4v left.
• current limit power-max: 2.4v*20mA = 48mW.
• Total Current: 20mA * 162 = 3.24A
• Total power: 3.24A * 12v = 38.8w

20v

• 20v/3.8 (V-max-led-forward) = 5.2 LEDs; 5 LEDs in a chain.
• There are 96.8 chains [484/5]
• Vmax = 5 * 3.8Vf = 19v; 1v left.
• Vmin = 5 * 3.2Vf = 16v; 4v left.
• current limit power-max: 4v*20mA = 80mW.
• Total Current: 20mA * 97 = 1.94A
• Total power: 1.94A * 20v = 38.8w

Components

• R1 = 100k
• R2 = 1k8
• Rs = 10
• Opamp >20v;
  • OPL best fit: LM358DR (But has two channels) -- €1.17 (100pcs) -- https://nl.aliexpress.com/item/10PCS-LM358DR-SOP8-LM358-SOP-LM358DT-SMD-LM358DR2G-new-and-original-IC-free-shipping/32533323519.html
  • *Single* channel opamp: LM321 -- €1.99 (100pcs) -- https://nl.aliexpress.com/item/Free-Shipping-100PCS-100-NEW-LM321MFX-LM321MF-LM321-A63A-SOT23-5/1924012475.html -- http://www.ti.com/lit/ds/symlink/lm321.pdf
• Mosfet. >20v; >20mA:
  • From the OPL: BSS138W-7-F; 50V; 200mA -- €1.36 (100pcs) -- https://nl.aliexpress.com/item/50PCS-BSS138LT1G-SOT23-BSS138-SOT-MOSFET-SMD-new-and-original-IC-free-shippin/32518915182.html -- http://www.onsemi.com/pub/Collateral/BSS138LT1-D.PDF

Verifying LEDs

The LEDs arrived. Lets verify their specifications

	I=20mA		I=15mA		I=10mA
Nr	V_min	V_max	V_min	V_max	V_min	V_max
1
2
3
4
5
6
7
8
9
10
Avg

Circuit

[from http://www.falstad.com/circuit/circuitjs.html]

$ 1 0.000005 10.20027730826997 50 5 50
w 544 592 416 592 0
w 416 576 416 592 0
v 416 576 416 176 0 0 40 20 0 0 0.5
g 416 592 416 624 0
w 416 176 544 176 0
w 544 176 544 336 0
f 688 464 752 464 0 1.5 0.02
162 752 272 752 320 1 3.2 1 0 0 0.01
162 752 320 752 368 1 3.2 1 0 0 0.01
162 752 368 752 416 1 3.2 1 0 0 0.01
r 752 528 752 592 0 10
w 544 592 608 592 0
w 608 592 752 592 0
w 544 560 544 592 0
w 752 480 752 528 0
w 752 528 608 528 0
w 608 480 608 528 0
w 544 448 608 448 0
a 608 464 688 464 1 12 0 1000000 0.11134962704993533 0.11137629276054098
r 544 352 544 448 0 100000
w 544 352 544 336 0
r 544 448 544 560 0 560
162 752 224 752 272 1 3.2 1 0 0 0.01
162 752 176 752 224 1 3.2 1 0 0 0.01
w 752 416 752 448 0
w 752 416 688 416 0
c 688 416 688 176 0 1.0000000000000001e-7 -14.836678863009816
w 544 176 688 176 0
w 688 176 752 176 0
o 26 64 0 4099 20 0.00009765625 0 2 26 3
o 6 64 0 4099 20 0.05 1 2 6 3
o 10 64 0 4099 0.625 0.05 2 2 10 3