Monthly Archives: July 2021

SLA Battery minimum discharge voltage

Recently I installed a solar panel. I used a 12 volts Sealed Lead Acid Maintenance Free battery with it. There was a huge lot of confusion as to what to set the minimum voltage or cutoff voltage. The charge controller came with a preset of 10.8 volts. But on the internet many forums and sites suggested to keep the cutoff voltage to around 11.5, some said I can go as low as 9.0.

Confused I started going through manuals or leaflets of battery companies and understood that it better to refer to the manual or leaflet or company information than to rely on the random articles and forum posts on the internet.
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Websites for buying electronics parts in India

Amazon.in – exorbitant prices. Often 3 or 4 times. There are sellers who will send wrong products. Amazon will initiate a replacement which has little chance of happening if the price of item is low.

Calcuttaelectronics.com — very reliable, parts quality good. But since 2020 (after the first lockdown) their variety and stock has gone down and as of date of writing many parts are “out of stock” for many weeks. Good packaging. Support was a little disappointing.

Electroncomponents.com — has a good collection and very cheap. But the price and variety made me a bit curious (and cautious), so checked the internet and found they had a very bad reputation in the recent past. But still I ordered and got my items in time.
Parts quality mixed – some are of good quality some are cheap ones. Packaging okay. Delivery time is good.

Iotwebplanet.com — parts are good, delivery times is good, variety is good, but orders may get cancelled silently. Has COD facility. Good packaging.

Robomart.com — They are reliable. Collection is okay sort of.  Parts are often good but not always or some parts can be quite cheap quality. Packaging good.

Tanotis.com — this is in a different league from the rest including Amazon. Most parts which are not available in any other websites can be found here. Quality is very good. But the delivery time is long and sometimes order gets cancelled (but they do inform and give refund). Though costly but is still reasonable than other sites in that league. Very good packaging.
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Atmega 8 pin mapping

Atmega8 to Arduino pin mapping

Here is an easy to refer mapping of Atmega 8 pins to Arduino.  Credit of this image goes to user called “System” on Arduino forum https://forum.arduino.cc/u/system/summary

The image has been taken from the post https://forum.arduino.cc/t/pwm-didnt-work-on-atmega8/248564

A neat and to the point image like this is rare on the internet. I have just put the image here as a mirror of the original to ensure availability.

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Places Search API Call

Here is summary of how to call Places search API of Bing, Google and Here Map.

Here is little known among most developers, specially developers of India, but it is a good API and there map is also very good. Their map have internal maps (floor layout) of many buildings.

Here Maps API Call

Below is the latest v7 API, all other APIs are obsolete
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Firebase Web Push Browser Issue

As of today, 2nd of July 2021. FCM libraries have some bugs due to which it fails to get tokens sometimes in Chrome browsers current version.

Errors that occurs :

  1. Uncaught (in promise) FirebaseError: Messaging: A problem occured while subscribing the user to FCM: Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project. (messaging/token-subscribe-failed)
  2. “Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project.

How to integrate Firebase Push Notifications for Websites: https://www.kolkataonweb.com/code-bank/miscellaneous/website-push-notification-with-google-firebase/