| ▲ | amelius 9 hours ago |
| What component values do you need to time exactly 55 years? Maybe it could work if you used 5 timers? |
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| ▲ | ua709 8 hours ago | parent | next [-] |
| How exactly is exactly? Can I make it measure 1 hour with an allowed tolerance of 55 years, plus or minus. :) |
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| ▲ | megous 9 hours ago | parent | prev [-] |
| I don't think you could do it. Not with the original BJT variant anyway. :) |
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| ▲ | floxy 7 hours ago | parent [-] | | Hmm, why not? For the astable configuration, you could use a 100F capacitor with R1 = 10 Meg and R2 = 7.5 Meg, for a 55 year period. Base current for the Threshold NPN will come from the Trigger PNP (and hopefully temperature drift matches OK). Other than maybe the 100F capacitor might have some variation in capacitance and leakage current over the course of 55 years ;-) https://www.digikey.com/en/products/detail/tecate-group/PBLH... | | |
| ▲ | speff 13 minutes ago | parent [-] | | Once you get above a couple meg, the oils on your fingers start affecting the resistance. Better hope no-one touches with your 55 year counter |
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