Fong LED 01

Introduction I found LM334  CCS's performance in high current mode not very satisfactory for current higher than 100mA.  So I am thinking of exploring other circuit designs. I quickly read the follow articles to get a rough idea of different CCC circuit designs. [1]  Active Transistor Constant Current Source - electronics-notes.com [2]  The Basic MOSFET Constant-Current Source June 06, 2016 by Robert Keim - aac [3]  Current Mirror BJTs - aac [4]  Simple constant-current driver - lednique [5]  Simple variable current source for approx 2A, constant load - EESE, 2017jun06 [6]  Current Limiting - Wikpedia   [7]  Current Source - Wikipedia After comparing and contrasting all these designs, weighing pros an cons, I am thinking of exploring the following circuit as described below: 1. One power MOSFET  2. One DAC 3. One current sensing amplifier. / to continue, ... 

Introduction Now I am using the LM334 high current circuit to test 1W RGBYW Power LED Lamps. The circuit uses a PNP BJT, so I am reading the cs9012 datasheet to refresh my memory.  So I wired up the LM334Z High Current Circuit to light up a 1W 350mA Ref power LED.  I have no idea to use for R1 and C1. For the first trial I just use R1 = 1k and no C1. I found results looks OK.   For Vcc = 5V, Current I through LED is 112mA, as show below. Next is to test other colours, Y, B, W. If all RGBYW LEDs ha more or less same value of current, then I can conclude that this preliminary CCS big current test is OK. I found the LED currents for the RGBYW LEDs are not equal, or nearly equal. The currents are: R = 112mA G = 95mA B = 81mA Y = 116mA W = 85mA Next is to try changing the value of the bais resister, and see if there is any improvement. Anyway, the 1W white LED is bright enough to take a clear photo, as shown below. Conclusion - Circuit seems not working, would troubleshoo...

Introduction This test uses a constant current source (CCS), instead of a voltage source, to control a RGBYW LED's brightness.   LM334 is used to test small current ( < 20mA) indicator and large current (< 350mA, 1W) power LEDs.  RGBYW The circuit used in this test is the most basic one, with a current limit of 10mA.   Now I am setting up the CCS test circuit with the following parameters: 1. Vcc ~= 5V 2. CCS = LM334Z 3. Measuring equipment, 2 dirt cheap multi-meters, one for voltage, another for current. 4. Rset resistor = 10 Ω (30 Ω  x 3 in parallel) 5. LED samples to test = as shown below. Now I have tested the ordinary and power LEDs shown below.  I found that the CCS circuits works very well, ALL the samples have a very "constant" value for 5V in the range of 6.80mA to 6.85mA. Next step is repeat the test without using the CCS, to compare results to show that if CCS is that effective. I tested RGBYW LEDs, and found that for RED LED, the aver...