It’s kind of convenient to be able to check current but I don’t need it to be particularly accurate
Mark > On Sep 23, 2015, at 8:10 PM, Forrest Christian (List Account) > <[email protected]> wrote: > > So, I think I've about got the design for the next iteration of injectors > nailed down, with one exception. > > I'm not quite sure what to do about overcurrent protection. > > Let me ask this question up front: > > How important is it to be able to read the current being drawn by each radio? > > In the current SyncInjectors, Airfiber injectors, and 5 channel PDU's, I do > active overcurrent protection. In short, the microcontroller measures the > current through each channel using a hall effect sensor and when it detects > an overcurrent it just shuts off the port. > > The advantage of this is that we get very rough current measurements (like > you can usually tell if a radio is on or off, or drawing more power than > normal, but NOT anything close to an exact measurement), and I can somewhat > adjust the response to the overcurrent to handle inrush and the like. This > is also fairly expensive per port (like they add around $5 per injection port > to the cost of the product). With the altered design I'm looking at the > current measurement accuracy would go up for around the same cost. > > On the other hand, In the past I've just used self-resetting (aka PTC) fuses, > which are simple and very robust, but don't end up with current reading as a > side effect since the microcontroller doesn't get involved. I can > definitely detect a overcurrent (aka fuse has been tripped) easily and > expensively, but can't tell how much current is actually being drawn. > > My decision is coming down to a perceived value choice. Is it worth $5/port > on an injector to be able to read the actual current used? > > -- > Forrest Christian CEO, PacketFlux Technologies, Inc. > Tel: 406-449-3345 <> | Address: 3577 Countryside Road, Helena, MT 59602 > [email protected] <mailto:[email protected]> | http://www.packetflux.com > <http://www.packetflux.com/> > <http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux> > <http://twitter.com/@packetflux> >
