Apr 16, 2015 #1 J Jester Full Member level 6 Joined Aug 18, 2012 Messages 377 Helped 7 Reputation 14 Reaction score 7 Trophy points 1,298 Location . Activity points 4,754 I have the need for a low frequency (say 1kHz) oscillator as follows: - Really inexpensive - Reliable start-up -40 +90 deg C - 0-5V output @ <10uA - Accuracy 20% - Duty cycle 25 - 75% - power source; +5Vdc The tried and true 555 circuit is pretty cheap: $0.44@qty10, or $0.22@qty100 (Digi-Key pricing) Does anyone have a cheaper or more elegant solution?
I have the need for a low frequency (say 1kHz) oscillator as follows: - Really inexpensive - Reliable start-up -40 +90 deg C - 0-5V output @ <10uA - Accuracy 20% - Duty cycle 25 - 75% - power source; +5Vdc The tried and true 555 circuit is pretty cheap: $0.44@qty10, or $0.22@qty100 (Digi-Key pricing) Does anyone have a cheaper or more elegant solution?
Apr 16, 2015 #2 andre_luis Super Moderator Staff member Joined Nov 7, 2006 Messages 9,632 Helped 1,190 Reputation 2,399 Reaction score 1,216 Trophy points 1,403 Location Brazil Activity points 55,854 Certainly not more elegant, but doing that with NAND is cheapest: $0.13@qty100 https://www.digikey.com/product-detail/en/CD4093BM96/296-25956-2-ND/1691444
Certainly not more elegant, but doing that with NAND is cheapest: $0.13@qty100 https://www.digikey.com/product-detail/en/CD4093BM96/296-25956-2-ND/1691444
Apr 16, 2015 #3 W wade_hassler Member level 4 Joined Aug 7, 2008 Messages 79 Helped 15 Reputation 32 Reaction score 11 Trophy points 1,288 Activity points 1,705 How about a single-gate Schmitt-trigger oscillator? Digikey has 74AHCT1G14SE-7DITR-ND at $0.0425/3000
How about a single-gate Schmitt-trigger oscillator? Digikey has 74AHCT1G14SE-7DITR-ND at $0.0425/3000
Apr 16, 2015 #4 D.A.(Tony)Stewart Advanced Member level 7 Joined Sep 26, 2007 Messages 9,576 Helped 1,847 Reputation 3,693 Reaction score 2,340 Trophy points 1,413 Location Richmond Hill, ON, Canada Activity points 61,879 'HCT14G may be best price readily available. But do you need to guarantee 20% accuracy with a 10% supply over wide temp with what tolerance cap?
'HCT14G may be best price readily available. But do you need to guarantee 20% accuracy with a 10% supply over wide temp with what tolerance cap?
Apr 16, 2015 #5 J Jester Full Member level 6 Joined Aug 18, 2012 Messages 377 Helped 7 Reputation 14 Reaction score 7 Trophy points 1,298 Location . Activity points 4,754 SunnySkyguy said: 'HCT14G may be best price readily available. But do you need to guarantee 20% accuracy with a 10% supply over wide temp with what tolerance cap? Click to expand... Actually for this application, the frequency is not critical at all, I can live with 50% accuracy. I like the proposed solution, not only is it less expensive, it uses a smaller package (SC-70 vs. SOIC8) and one less component. Thank you.
SunnySkyguy said: 'HCT14G may be best price readily available. But do you need to guarantee 20% accuracy with a 10% supply over wide temp with what tolerance cap? Click to expand... Actually for this application, the frequency is not critical at all, I can live with 50% accuracy. I like the proposed solution, not only is it less expensive, it uses a smaller package (SC-70 vs. SOIC8) and one less component. Thank you.
Apr 16, 2015 #6 Audioguru Advanced Member level 7 Joined Jan 19, 2008 Messages 9,461 Helped 2,152 Reputation 4,304 Reaction score 2,009 Trophy points 1,393 Location Toronto area of Canada Activity points 59,764 The ordinary 555 with a 5V supply has an output that is a minimum of only 2.75V if it has no load. The 555 draws a fairly high current all the time.
The ordinary 555 with a 5V supply has an output that is a minimum of only 2.75V if it has no load. The 555 draws a fairly high current all the time.
Apr 17, 2015 #7 D.A.(Tony)Stewart Advanced Member level 7 Joined Sep 26, 2007 Messages 9,576 Helped 1,847 Reputation 3,693 Reaction score 2,340 Trophy points 1,413 Location Richmond Hill, ON, Canada Activity points 61,879 CMOS version of 555 takes 30uA https://www.digikey.com/product-detail/en/ICM7555ESA+/ICM7555ESA+-ND/1303147
CMOS version of 555 takes 30uA https://www.digikey.com/product-detail/en/ICM7555ESA+/ICM7555ESA+-ND/1303147
Apr 17, 2015 #8 KlausST Advanced Member level 7 Joined Apr 17, 2014 Messages 25,807 Helped 4,907 Reputation 9,837 Reaction score 5,706 Trophy points 1,393 Activity points 172,984 Hi, any comparator should do. and three resistors and a c. plus a c for vcc decoupling. it is very stable in time and has good stability on VCC change. Temperature drift is more a problem of the used C. I don´t know if this solution is cheaper than others. Klaus
Hi, any comparator should do. and three resistors and a c. plus a c for vcc decoupling. it is very stable in time and has good stability on VCC change. Temperature drift is more a problem of the used C. I don´t know if this solution is cheaper than others. Klaus