Thanks Acidbrain,
That must be it. The shorter lead is negative from the battery tests etc. Then my problem was that the Wikipedia page on LEDs that I was counting on to be an authority has a picture of an LED that is the exact reverse of mine.
Unhelpful picture for me
OK Salas,
I am getting all LEDs on now, the first two are very bright and the third is dimmer, and the last two with the 3K3 are also dim. I have 3.9Vdc at the output terminals.
I am getting all LEDs on now, the first two are very bright and the third is dimmer, and the last two with the 3K3 are also dim. I have 3.9Vdc at the output terminals.
Replaced dim led - now I have 3 bright leds in first set & 2x dim ones in 3K3 resistor loaded set.
4.21Vdc at output pins
1.08Vdc across 3K3 resistor
1.714Vdc across 10R 5W
Heatsinks understandably quite hot.
Shall I replace those 2x dim leds?
4.21Vdc at output pins
1.08Vdc across 3K3 resistor
1.714Vdc across 10R 5W
Heatsinks understandably quite hot.
Shall I replace those 2x dim leds?
Replace those other 2 dims, and the Jfet over the 1R position. You should get something in the 20s for Vout with a 3k3. Then you will do V3k3/3k3, will show the current through it. By Vout-V3k3 we will know how much more R for 30Vout.
I am out in a bit, the guys will help you mean time. I will be back later.
I am out in a bit, the guys will help you mean time. I will be back later.
Hi,
that Wiki pic looks right even though the pic has the leads truncated.
short lead is on flat side and big electrode side.
Remember that an LED is forward biased to emit light, i.e. the arrow part of the symbol points in the direction of conventional current flow (from +ve to -ve).
OK, calm, calm!
Replaced K170 by 1R, & both leds. Same story. Voltages almost identical to before. I must have killed something else.
Replaced K170 by 1R, & both leds. Same story. Voltages almost identical to before. I must have killed something else.
The short legs on my leds, which are Panasonic (Digikey part no P605-ND) are on what is clearly depicted in this picture as the Anode side (ie. having a smaller part that does not house the diode itself). Not only that but there's no useful flat side and now I've destroyed some of my components as a result. I am thoroughly F**king confused and in a really bad mood now.
What happens in a circuit when an LED is installed backwards, is it still a diode and blocks current flow?
I believe that they only work in one direction, and stop flow altogether if reversed, although I'm not 100% sure
yes, it's a poor diode and fails at quite low voltage. More like a zener and the heat kills the LED.
test them first.
Label the +ve lead if necessary.
Or stick a tiny bit of tape on the -ve side of the LED to remind you where the flat should be.
Just to confirm that I've tested with 9v battery and 2K resistor, with 2K resistor between + terminal of battery and long leg (+) of led, I have light.
Also to confirm, that that Wikipedia picture is not universal, and my leds are visually the opposite way around (inside the plastic I mean).
Now I don't know what to do? Am I going to have to buy some more 2SK170s and replace them all?
Also to confirm, that that Wikipedia picture is not universal, and my leds are visually the opposite way around (inside the plastic I mean).
Now I don't know what to do? Am I going to have to buy some more 2SK170s and replace them all?
you can test you k170 as well.
Same 9V battery and use 100r if you have it.
Measure the voltage across the 100r when drain is +ve and gate and source are shorted to -ve.
Each mV across the 100r indicates a current of 0.01mA
6.7mA Idss would indicate 670mV
The 2 matched pair in the B1 part should not be damaged if the voltage never went opposite polarity and never went to greater than 30V total across +ve to -ve.
Of the remaining 6 jFETs in the shunt regulator, two must be k170 the other 4 can be any cheap low transconductance. I use BF244b since they have identical pin out.
Same 9V battery and use 100r if you have it.
Measure the voltage across the 100r when drain is +ve and gate and source are shorted to -ve.
Each mV across the 100r indicates a current of 0.01mA
6.7mA Idss would indicate 670mV
The 2 matched pair in the B1 part should not be damaged if the voltage never went opposite polarity and never went to greater than 30V total across +ve to -ve.
Of the remaining 6 jFETs in the shunt regulator, two must be k170 the other 4 can be any cheap low transconductance. I use BF244b since they have identical pin out.
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3.9Vout spells Vgs to me. The Mosfet is probably OK. Jfet changed... What about having killed the BC550?
Replaced with my last spare jfet.
I will change the BC550 with the one I have spare, then try again, if you think that's the right thing to do.
Before I do that, have a look at my board lights:
Shunt_Reg_Blues_2 - My Photo Gallery
Here is the data sheet of the LED's you are using. maybe someone can see if it's the LED's
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