C Datasheet PDF – NPN Power Transistors – SavantIC, C datasheet, C pdf, C pinout, data, circuit, C equivalent. CAU5F  – C TRANSISTOR NOS(New Old Stock ) 1PC. CAU5F PART NUMBER REPLACE PART SUMMARY. NTE – NPN Transistor, SI High-Voltage/High-Speed.
|Published (Last):||24 December 2015|
|PDF File Size:||19.36 Mb|
|ePub File Size:||17.50 Mb|
|Price:||Free* [*Free Regsitration Required]|
Essentially I know the circuit works. The only hold-up is that I have tried two trnsistor NPN transistors salvaged from old CRTs and both end up with Vce voltages around 35V causing them to heat up rather quickly since the current is around 1 amp.
I will link the datasheets transishor the two in below. I have measured the output of the timer at 2V RMS and set the resistor values for each transistor according to their Ib vs Vce graphs around 0.
2SC3866-2SC 3866-C3866 TRANSISTOR-N 900V 3A 40W
Fuji C Toshiba 2SC https: You can’t bring Vce down – you are operating it with pulse width modulation therefore the transistor is trqnsistor fully-on of fully-off. What you may measure is the average Vce. And now to the main issue – you are not controlling the current it seems from your circuit diagram – there is nothing to rransistor the PWM duty cycle – there is no current feedback hence it is open-loop voltage control.
The next issue is you need an inductor and capacitor to filter the “strong” square wave delivered by your switching transistor – the peak voltage across the LEDs will be basically rectified AC and this could kill them unless there is internal current limiting but, if there is then why both with this ornate solution? You must not treat a string of LEDs as having a resistance! LEDs have a very sharp voltage-current relation. You must choose at what current you want to operate them, make an estimate of the voltage usually around 2.
Your LED current is unlimited, no wonder they burn out. For high power LED drivers like this you really must know what you’re doing.
Be able to make power calculations etc. Also Volts transistog dangerous, 1 A through the transistor. Are you sure you know what you’re doing?
C(TRANS) NTE Equivalent NTE TRANSISTOR NPN SILIC – Wholesale Electronics
Your problem is much more fundamental to your design. Please educate yourself first before proceeding. What you need to learn first cannot be explained here in a few lines.
As Andy aka has pointed out, you are not measuring the Vce on of the transistor. You are measuring the average Vce in the presence of the PWM, and you should expect that to be much higher than Vce on. However, since you seem to be having heat problems, I’ll assume that your transistor is not being properly driven. Your problem is most likely that you are not able to provide enough base current to turn the transistor fully on. The rule of thumb is that, when a transistor is in saturation, it has a gain of about 10 to This means that, for a load current of 1 amp, you’ll need about mA of base current, which should be well within the capabilities of a Actually, from the data sheet, at 1 amp collector current, a mA base drive will only drop your Vce to 5 volts using the C, so I don’t recommend using it.
Note that hfe is the same as beta. Use the other one. You need to keep in mind that, with a 5 volt supply, a putting out. Furthermore, the Vbe will be about 0. So the resistor should be about 10 ohms. I’ll disagree with Andy about your filtering. I believe that your cap is adequate. I’d recommend that you double-check the LED current. Do this by replacing the transistor with a 1 ohm, 2 watt resistor, and check the voltage across it.
Home Questions Tags Users Unanswered. Trey Carpenter 6 2. Bad, bad circuit it seems. Take a look at this: Andy aka k 10 Very bad indeed, those poor innocent LEDs burnt to crisps: Ok, first of all thank you for your feedback.
Foremost, the inductor and feedback diode seem like a very good idea. Second, I probably should have indicated that I am used 9x 10W 12V LEDs which I did a few tests on before hand to obtain a general range of internal resistance. You just cannot hope for the best that things won’t drift. Maybe the LEDs themselves are better protected internally and this saves the day as you believe but I cannot check this as I don’t have a data sheet or part number I’m not going to follow ebay links btw – if it aint got a data sheet pdf I wouldn’t buy it!
I have considered and addressed your comment in the one above. I don’t know what I’m doing – this is a learning experience.
OK, some comments on your new schematic: Ground at bottom right: You still do not have the required current limiting for the LEDs in place, you added L1 but it is useless here. Andy’s circuit has an inductor but that is because the IC that is used there is a switching converter with current feedback.
You have nothing c386 that sort.
Same for D0, not needed. You think you control Vce by changing R2 but you’re c38666. But I measured Vce! Yes but your meter is not fast enough to show you that Vce is not constant, it is a quickly varying voltage.
The only way you can make this design usable is to add resistors in series with the LEDs. But do take power dissipation into account.