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  • gdriver commented on moekoe's instructable DIY Dashbutton for the Internet of Things6 months ago
    DIY Dashbutton for the Internet of Things

    Looking at https://www.tinyosshop.com/datasheet/ESP-07S_User_... I see that the can of the 07S is slightly bigger than that of the 07 so I am wondering if the required resistors are now inside the can?Someone queried the the absence of ext antenna - on the ESP07 there was the option of using an on-board ceramic antenna. This seems to have vanished on the S so I guess an external antenna is required - as per document.Your LiR2450 is rated at 3.7V nominal and 200mA maximum. The ESP tpically draws over 250mA peak during transmit unless you add 1000uF or so across the 3.3V rail. The regulator drops 200mV at 200mA, so 3.3V+0.2V=3.5V -- not a lot of headroom here. http://ww1.microchip.com/downloads/en/DeviceDoc/20... fig. 2.20 shows a 2.8V output dropping by 200mV with a 200mA step load. T...

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    Looking at https://www.tinyosshop.com/datasheet/ESP-07S_User_... I see that the can of the 07S is slightly bigger than that of the 07 so I am wondering if the required resistors are now inside the can?Someone queried the the absence of ext antenna - on the ESP07 there was the option of using an on-board ceramic antenna. This seems to have vanished on the S so I guess an external antenna is required - as per document.Your LiR2450 is rated at 3.7V nominal and 200mA maximum. The ESP tpically draws over 250mA peak during transmit unless you add 1000uF or so across the 3.3V rail. The regulator drops 200mV at 200mA, so 3.3V+0.2V=3.5V -- not a lot of headroom here. http://ww1.microchip.com/downloads/en/DeviceDoc/20... fig. 2.20 shows a 2.8V output dropping by 200mV with a 200mA step load. The capacitor will prevent this. Microchip do not show a 3.3V regulator operating with an input voltage as low as of 3.7V.You might like to look at https://www.youtube.com/watch?v=heD1zw3bMhwAlso on V3 you might like to consider that the quiescent current of the LED is typically 0.7mA - your battery will last only a few days - maybe add a high-side switch along the lies of FDC6329L https://www.mouser.sg/ds/2/149/FDC6329L-1007185.pd...

    Nice looking, but from what I have read -GPIO 0 should be high on normal boot, you have it floatingGPIO 15 should be low at power-up, again floatingEN should be pulled high through a ressitor not tied directly to VccThese things can lead to unreliable operation (alledgedly)

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  • gdriver commented on geekrex's instructable The Ultimate 1 $ Emergency Light3 years ago
    The Ultimate 1 $  Emergency Light

    TI datasheet says the min. recommended volts drop is 3V, and it doesn't come in T092. Apart from that...

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  • gdriver commented on geekrex's instructable The Ultimate 1 $ Emergency Light3 years ago
    The Ultimate 1 $  Emergency Light

    If you have no way to know what the current will be there is every possibility of the wiring or battery burning with different LEDs

    HiYou are worried that 10 LEDs should need 10 x (3 to 5V). Worry not - these LEDs are in parallel so only need 3V to 5V.What you should be worrying about is the lack of any kind of proper current limiting - this innocent may have got away with it - the current will be set by whatever resistance is in the battery/wiring and whatever vots these LEDs happen to operate at. This is a BAD circuit.

    HiYou are worried that 10 LEDs should need 10 x (3 to 5V). Worry not - these LEDs are in parallel so only need 3V to 5V.What you should be worrying about is the lack of any kind of proper current limiting - this innocent may have got away with it - the current will be set by whatever resistance is in the battery/wiring and whatever volts these LEDs happen to operate at. This is a BAD circuit.

    HiWhat worries me is the lack of any kind of proper current limiting - you may have got away with it - the current will be set by whatever resistance is in the battery/wiring and whatever volts these unknown LEDs happen to operate at. No fuses either. This is a BAD circuit.

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