circuit design evaluation - Page 1
Forum section: electronics / projects

author: dins
author_rank: Newbie
timestamp: January 06, 2020, 01:38:54 pm
content: Hello again all! hope you are enjoying the start of your new year.So i have been ever so slowly working on a portable bluetooth speaker project and the most electronics focused portion of it i am ready to start testing as a complete unit. but i would like opinions. If my design is the right way to go about doing what i want, pointing out things that may cause long term issues, things i may have missed etc. also i am by no means an expert so please try dumb things down if you can!attached is a picture of the schematic, but the purpose of this one circuit board: it ties a bunch of other separate electronic parts together: a speaker amp, battery (with a bms) and external power source, usb charge board, battery charge board, speaker crossover housing, on off power toggle.so i hope that explains the general purpose of the board, but let me explain in more detail the segments of it.the flip flop section handles switching power to the load by the toggling of a single button, i initially did not have R5 in the design but with a bit of testing i found the fets would not behave as expected if handling a big load but adding a bit of resistance inline with the gate solved that.the battery charging and isolating section provides another fet switch but for the purpose of isolating the battery from the load so it can be properly charged, if voltage is applied externally via the 14v socket it will shut off the fets (hopefully i have not tested that as i write this), a single diode lets power flow from the 14v socket to the flip flop power side instead of the battery so the amp can still run while it charges.the usb charging board output has a diode junction so that power from the 14v socket can power it, its always on regardless of the flip flop state, or when no 14v supply is plugged in, power from the battery when its turned via the flip flip can then power the usb charger, as well as the amp.the speaker crossover is pretty simple inductor and a capacitor to filter out low frequencies from the tweeter.thats about it, there are a few little capacitors placed around that i dont know what they do but they are part of the flip flop and battery isolation designs i saw. there is a 100k resistor, R3 that i think will help drain any residual power from triggering the gate when the external power supply is removed guaranteeing that the battery reconnects. does the flip flop gate line need one? the flip flop seems to work fine with out it in my tests, unless R2 is acting like one.im trying a one layer pcb i routed out on my cnc machine for prototyping but once it all proves to work well and no one sees any issues or i fix any issues i may get a few boards properly made else where as i want to make a few of these speakers! i will do a final pcb design after its all sorted out here.also on the last note, the toggling of power that the flip flop portion is designed to do, while it works, it works not as intended, you have to double press for it to start, but single press and it will turn off, i guess something with the load effects it all? i may give up on the flip flop and just use a normal toggle switch.