Yo yo yo. What up homies? I am once again humbled to be in need of your gracious assistance. I did all the work this time. I would just like some fresh minds to double check. I am driving two relays with this transistor. This is the relay. It's coil is rated at 11.6mA.(adsbygoogle = window.adsbygoogle || []).push({});

Now here comes the tricky part. I chose a 7.5KOhm resistor. I looked at the datasheet for the transistor and saw that the minimum Beta (Current Gain) was 100. I used 50mA as my target Ic and got .5mA as my Ib. Now, 5V go into my PIC, 4.3 come out. On top of that, 0.7V is lost from the base to the emmiter, right? So I now have 3.6V/.0005A = 7200Ohm. And I chose 7500Ohm, because the part was the best fit. Is that all correct?

I have two other transistors that power some other relays. I did all the math the same way, except that they are Darlington's so I used a 1.4Vbe. the only thing I'm pretty wary on is whether I used the right value for Beta. I used 750. Can someone confirm or deny this? Datasheet.

Ok. Now we come to the good ol' TVS diodes. This is what I chose. The clamping voltage is 64.5V. The transistors have a max voltage of 100V. Gravy, yeah?

Thanks for the soon-to-come help.

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# Double check base resistance values and TVS diode choice, please.

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