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I have a problem in powering the Nodemcu v1.0 ESP-12E using 9v-1Amp DC external power supply and 7805 voltage regulator(which has heat sink).

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I am doing a project using Nodemcu v1.0 ESP-12E. Nodemcu v1.0 is connected to W25Q64 flash storage module, LDR module and DS1302-RTC module which are purchased from below websites.

RTC Module https://robu.in/product/ds1302-rtc-real-time-clock-module-with-battery/

LDR Module https://robu.in/product/lm393-photosensitive-light-dependent-control-sensor-module/

w25q64 flash Storage https://www.flyrobo.in/w25q64-64m-bit-flash-storage-module

9v 1A, DC adapter https://www.flipkart.com/balrama-9v-1a-dc-power-adapter-ac-smps-supply-9-volt-1-amp-adaptor-charger-worldwide/p/itm9e95a3fd665e8?pid=WWAGW3HCYHBHH6NZ

When Nodemcu v1.0 is connected to computer through USB port, there is no heat generated at LDO present on the Nodemcu.

I removed the USB power cable and I supplied the power to Nodemcu v1.0 through the Vin pin, I have used 9v-1Amp DC external power supply and 7805 voltage regulator and I have connected the 7805 output to Vin pin. To monitor the current consumed by the Nodemcu v1.0. I have connected Multimeter in series to 7805 voltage regulator and Nodemcu v1.0.

The current consumption started at 100mA, slowly in 30seconds it fluctuated and reached 120mA and after another 30seconds, the current consumed reached 140mA like this current consumption is slowly increasing and the 7805 voltage regulator and the LDO present on Nodemcu v1.0 are getting slowly heated up. So I stopped this experiment as I might cause thermal runaway and might burn something in this process.

Instead of using 7805, I have used 7806 with 9v 1A DC adapter and above problem has repeated.

My question is, whether this is a normal thing or am I doing any mistake in powering the Nodemcu v1.0. If there is any mistake please let me know, as I will understand the problem which I am facing.

If this is a silly issue, then suggest me a solution to power the Nodemcu v1.0 using External 9v 1A DC power supply.

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    \$\begingroup\$ Did you calculate the Watts being dissipated in the 7805 at 100mA? \$\endgroup\$
    – Aaron
    Commented Sep 25 at 17:20
  • \$\begingroup\$ @Aaron,i am not able to understand your question. Just after switching on the power, the current consumption is increasing linearly for every 10 seconds, so where exactly i can do the measurement ??? \$\endgroup\$
    – arjun kumar
    Commented Sep 25 at 17:32
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    \$\begingroup\$ The current increasing can be normal, it just depends on what the code is having the module do. ie. turn on bluetooth, turn on wifi, change oscillator freq. etc. You measured 100mA at the start, what is that power? Is it enough to make the regulator hot? \$\endgroup\$
    – Aaron
    Commented Sep 25 at 17:36
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    \$\begingroup\$ Almost. The Power is (Vin-Vout) * I. So (9V-5V) *100mA = 400mW. This is enough to make that little part toasty from the start! You can lower your Vin to lower the power dissipated, but the 7805 needs at least 2V of overhead to operate, or Vin=7V. You can get an LDO that needs less than a volt of overhead and drop your Vin, and that'll drop your wasted power a lot. \$\endgroup\$
    – Aaron
    Commented Sep 25 at 17:55
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    \$\begingroup\$ @arjunkumar There is some cooldown timer for users with low reputation. 24 hours or something similar. It should appear soon. \$\endgroup\$
    – winny
    Commented Sep 26 at 14:35

1 Answer 1

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@Aaron, what u have said is correct. I reduced the input voltage given to 7805 voltage regulator using DC to DC buck converter. https://robu.in/product/lm2596-hv-dc-dc-buck-converter-4-5-50v-to-3-35v/ .

I have connected 9v 1A DC SMPS power supply to the DC to DC buck converter and I reduced the 9v to 7v and I supplied this 7v to 7805 voltage regulator as input. The output of 7805 is connected to Vin of Nodemcu ESP-12E. Now there is no heating issue on 7805 and also no heating issue on LDO present on Nodemcu ESP-12E.

The Nodemcu ESP-12E consumes only 160mA when running a Espwebserver. 🙏 🙏 🙏 Thanks for the help.

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    \$\begingroup\$ Thanks for posting your solution. Note that on SE sites there is a "Accept" button to mark an answer as solving the question (rather than editing the title). When done properly it signals to the site engine that it can stop seeking an answer and won't keep posting it as unsolved on the home page. \$\endgroup\$
    – Transistor
    Commented Sep 26 at 12:33

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