| Electronics > Beginners |
| what is for "CURRENT REGULATOR DIODE"? |
| (1/4) > >> |
| 001:
what is for "CURRENT REGULATOR DIODE"? |O Can I replace 1N5303 with some transistor circuit? I see https://en.wikipedia.org/wiki/Constant-current_diode but how to calculate values? :-// |
| rstofer:
The current limiting diode attempts to provide a constant current flow over a large voltage range. If you need a current source, this is one way to get it. I'm not going to do the math but it seems like you can achieve the same thing with a zener diode and transistor and maybe even just a transistor. Or substitute an LED for the zener diode. https://en.wikipedia.org/wiki/Current_source#Simple_transistor_current_sources |
| Zero999:
It's just a J-FET with its gate tied to the source and is selected to give 1.6mA. https://www.mouser.co.uk/datasheet/2/68/1n5283-5314-43522.pdf You can make your own with a J-FET. Most J-FETs have a higher current than 1.6mA, with zero gate voltage. To get such a low current, you'll have to connect the source in series with a resistor. J-FETs have a wide spread of characteristics, so the resistor value to get 1.6mA will have to be determined experimentally. |
| exe:
These are not on sales anymore :( But discrete jfets are still possible to buy, though there are not that many around. |
| Benta:
1N5303 is available from several suppliers: Central Semiconductor, Digitron, Microsemi... You can make current regulator diodes yourself from JFETs, but the current spread is huge (1:3 or more). The "ready made" types are within +/-10%, much easier. |
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