Running Shruthi-1 With 9V Battery

Would this work? And any ballpark guess how long it’d last? 5/50/500 minutes? I’m guessing it’d vary depending on filter board and LED brightness…

Works. But i can’t tell how long…

Great! Being a dad to 2 little girls, windows of time to mess with the Shruthi-1 can open and close at a moment’s notice, so being able to flashmob a setup with all-battery gear (oxygen8, little gem amp) would be priceless. I’ll grab a couple next time I order some headers. Thanks, Frank!

Check the mAH ratings of the battery, divide by the current consumed by the Shruthi to get the battery life in hours. Don’t remember how much the Shruthi drinks, but it’s in the 100-150mA range. More (up to 200mA) if you have a fancy LCD. The filter board takes 15mA to 40mA depending on its complexity (Rule of thumb: 5mA per IC). Big guzzler is the LCD.

Hot stuff. A couple hours off one lithium rechargeable would be fantastic!

If thats not enough try 2 in Parallel

IMO if you want to run a shruthi on battery, it’s worth adding some switching thing for the lcd screen backlight. Shouldn’t be very difficult (a switch in series with a resistor)

Good idea. The backlight resistor is the 68 ohm one on the control board. Remove it and solder a switch + resistor there.

you will get a couple hours off a standard alkaline one no problem. I did some test when building the triple one and I was getting a at least 3 hours (I didnt test for more than that)

You might look at something like this:

I’ve got a similar 12v one that came with a home automation controller so you can carry it around and pair it with switches.

I went with 6xAA rechargeable batteries (in two block holders in series) because the ones I have vary from 1300mAh to 2800mAh whereas the 9V PP3 ones only store 200mAh.

18650 lion cells are handy. I have a battery holder for those which some guy used to make.

A note on voltage: the board works at +/- 5V. Any voltage in excess of that is turned into heat by the regulator. For example if the board sucks 150mA and is powered by +9V ; (9 - 5) * 0.15 = 0.6W are just lost into heat at the regulators. Which means that if you follow the AA batteries route, you can just remove one from the pack (and short it) to provide 7.5V instead - whatever power provided by the 6th battery would be dissipated by the regulators! Removing another battery from the pack wouldn’t work, 6V is too low, 78xx and 79xx typically need 1.5V of “headroom” above the target voltage.

If you want to be fancy about battery, you can replace the 7805 / 7905 by more efficient regulators (such as LM2940 / LM2990) which would work with a 6V input since they need only 0.6 … 0.8V of “headroom”.

18650’s are 3.7 volts, so two gives you 7.4 which is enough. All depends if you like Lithium Ion batteries, they do need to be looked after so they don’t explode :slight_smile:

Shruthi-1 make nice hand warmer on long cold night :slight_smile: thanks for the info regarding extra AA