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Delay on timer and SSR

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jmx66

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Hi all,

I only need a power on delay circuit, roughly one second or two,to energize a SSR.

The original board had a 2PST relay, and cut Live and Neutral , so i use also 2 SSR, in this schematic.

I found 2 circuits on the web, and had questions about .

LM555

My choices:

-Current :10 mA for the LS240D12 , sufficient to work and get a safety margin?

- Delay: R1 =10 kOhm C1 = 100 µF T= R.C ≈ 1s

- R2 : 10 kOhm 1/2 W

2N3904

I made a mistake for Ib !!!!

Ic/ Ib = 10 so for Ic = 10 mA I got Ib = 1 mA Right?

Math for Rb: Rb= ( Vs -0,7) (2.Ib) Rb= 4150 Ohm and 1/2 W

R1 and C1 as above.


As usual, could it work?

Thanks a lot and happy new year to members and your families.

Regards.

jmView attachment 2N3904.pdfView attachment datasheet-LM555.pdf Alim-Delay-with-LM555.pngView attachment l_s.pdfAlim-Delay-with-2N3904.png
 

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