Current for U2 is a series circuit, fed from the control board, through R9, through U2, then Q9 and completing the circuit to ground through U1. Being a series circuit, current flow is the same throughout the circuit (ignoring the few uA of Q9 base current). U1 is limiting the whole circuit to a maximum of 8mA. U2 will turn on at 3mA, but may not be fully on. I need to do some more testing to verify operation. If U2 doesn't produce full voltage, Q7 & Q8 may also not fully turn on, which would generate quite a bit of heat.
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Q9 is what switches U2 on from the control board signal. U1 is what switches U2 directly from the DC detection circuit. They are redundant circuits for safety.
U2 actually produces twice the required voltage to switch Q7 and Q8 off and on too. More safety measure, so if there was a problem in the control circuit (like someone misreading a datasheet!), Q7 and Q8 should never be half on. As an extra added safety measure, if any part of the whole board were to fail open circuit, everything will shut down.
U2 actually produces twice the required voltage to switch Q7 and Q8 off and on too. More safety measure, so if there was a problem in the control circuit (like someone misreading a datasheet!), Q7 and Q8 should never be half on. As an extra added safety measure, if any part of the whole board were to fail open circuit, everything will shut down.
Yes Q6 tells the control board things are good. Current from R10 makes Q6 pull the signal to the control board low. This is a fault condition. U1 grounds Q6's base, so no current will flow through Q6 in normal operation.
This is a failsafe part of the DC detection circuit. If U1 doesn't receive current from rail voltage and the DC detection circuits, it won't pull the base of Q6 low, triggering an alarm state on the control board.
This is a failsafe part of the DC detection circuit. If U1 doesn't receive current from rail voltage and the DC detection circuits, it won't pull the base of Q6 low, triggering an alarm state on the control board.
I've been looking at data sheets for optocouplers. The parts that deliver more current are slower. Plus I don't see matches for the pinout of the device the boards are designed for. To save the all ready built boards how about paralleling two chips. Easy enough to solder another part piggyback on top of the all ready installed part.
Hi all, as of yesterday I have two working honey badger channels that are going to need protecting. I've looked over this thread and am interested in building this design. I've noticed that the schematics, designs and code appear to be on a per request basis. Could someone point me in the right direction in terms of getting started with this. I'm very familiar with arduino programming and software development in general so that side probably won't be an issue.
Hi daavelovesvinyl,
The schematic and the layout are published in the thread, however, for the latest amendments/corrections please contact member Jwilhelm.
Would you like to do everything yourself (need the gerbers), or you'd like to buy the set of boards, or kits, etc.?
Cheers,
Valery
I'm still running reliable without the 470k resistor, but it's likely a good idea to add it.
