MMBT5551 and 5vdc relay

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hi. trying built relay module using mmbt5551 transistor switch relay on , off esp8266 or arduino board. schematics following, attached.

my problem is not switching relay on , off. have measured voltage across collector pin of mmbt5551 , 5vdc, shows 4.75 , 4.35 volts when switch io pin on esp8266 high or low. however, on connecting relay +5v , gnd directly, works (means relay working).

when try relay module (purchased ready made), relay switched on , off. of relay modules use bc847 transistors. transistor problem?

don't think so, looks resistor values high.

for values without measurements try -

the 47k going base of transistor, should more 2k2 4k7.

same led resistor, @ 10k never light, 330 470 ohms more suitable.


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