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  1. kellys_eye

    Issue in running BLDC motor with microcontroller

    Keep using the sensor! The torque will be a function of the PWM (drive signal) period and should vary according to the load - in other words you NEED to sense the rotational speed in order to feedback to the PWM circuit (or software) to compensate for motor load and output more current to the...
  2. kellys_eye

    Pool shooting robot needs help with rail-gun pool-cue thruster

    Thanks for those links - I'm a fan of the Instructables site and often in awe of the capabilities of the members! I'll be looking forward to seeing progress.
  3. kellys_eye

    Reading from 4 identical sensors using a Raspberry Pi...

    You're discovering that logic high and logic low can fall with a 'range' of values and not necessarily be +5V (or +3.3V) and ZERO...... Going back to your original idea, you can use transistors (better to use small FETs) to switch the supply lines to the sensors. Look for logic-compatible FET...
  4. kellys_eye

    Trying to re-purpose high voltage power supply. Need help

    Firstly - any power supply you build will have to dissipate the product of the input-output voltage multiplied by the current being drawn. For a supply with a 63V input and 15V output that's drawing (say) 5A you will have to regulate (dissipate) (63-15)*5 = 240 watts!!! A lot of waste (heat)...
  5. kellys_eye

    Making bad audio better

    To the OP - given a starting point amplifier of 'standard quality' it would be difficult indeed to improve its performance to a degree that a normal user would notice or in a financially worthwhile sense. I'm not talking about changing the 'colour' of the sound - you can make improvements by...
  6. kellys_eye

    Resistor across LED

    Is the port bi-directional and does the programming call for a logic high on that port, reconfigured as an input, during operation?
  7. kellys_eye

    Trying to re-purpose high voltage power supply. Need help

    I'd guessed they were a pi-type filter - capacitors across input and output with a series inductor between them. The picture showing them in-circuit appears to show the neutral line connected to only one of them too.
  8. kellys_eye

    Trying to re-purpose high voltage power supply. Need help

    Like I suggested measure the resistance from one terminal to the other. If it shows a 'short circuit' then they go as I said. If they measure open-circuit they go across the line/neutral as davenn says.
  9. kellys_eye

    Trying to re-purpose high voltage power supply. Need help

    I suspect it's an in-line filter module. The internal capacitors are likely connected to the casing. Most such filters I've seen have two terminals at each end for the live and neutral in/out but IIRC the older, higher power, versions had one such for each line. The resistance check should...
  10. kellys_eye

    Troubleshooting OZ811 dc-dc controller - showing negative voltage on output?

    ...oops. The control IC is one of those that requires specialist desoldering equipment (a QFN package). Not much chance of successful replacement I suspect. Sadly, with the original fault making one of the switching FETs go 'hard on' (giggidy) it really does point to the IC being dud.
  11. kellys_eye

    Troubleshooting OZ811 dc-dc controller - showing negative voltage on output?

    The kHz should be relatively stable but the duty cycle will vary according to load. Seriously - just replace the control IC and two MOSFETS. If they blow 'again' then you've got problems downstream of that regulator that may result in condemning the equipment!
  12. kellys_eye

    Trying to re-purpose high voltage power supply. Need help

    Yes, that's how the filters are connected. Measure between the two terminals and report your results (resistance). Measuring the AC at 14/15 on the transformer shows 18VAC (?) which, under normal circumstances, will rectify/smooth to approximately 26-28V DC across C5 (terminal 2 -ve, terminal...
  13. kellys_eye

    Troubleshooting OZ811 dc-dc controller - showing negative voltage on output?

    o_O NO! Do not link +Vin to LX - disaster will ensue! I was referring to you breaking the circuit (track) between PL14 and the point marked 22.8A and connecting a fixed load resistance to the junction of PL14/PR242 and ground. With a fixed load in place the output of PU14 should be measurable...
  14. kellys_eye

    4th July

    Scottish independence is a much reported red-herring given that the majority DON'T want it. No point in being 'independent' if you're entirely reliant on a 3rd party (the EU). Hypocrisy in the extreme. But I see where you're coming from :D
  15. kellys_eye

    Does anyone know what this connector type is called?

    Make? Model? Could be a manufacturers proprietary part - underhand means of tying you to purchasing their eye-wateringly priced replacements. When I come across such methods I tend to refit 'standard' plugs and sockets in place of them - but I'm the original skinflint :D
  16. kellys_eye

    Troubleshooting OZ811 dc-dc controller - showing negative voltage on output?

    Can you 'scope LDR? It shouldn't be a 'fixed' voltage (PWM) but you won't be able to tell with a simple multimeter anyway. Then again, if it WAS a fixed DC then the switching FETs would be 'hard on' and you'd be seeing the magic smoke! Simplest method to test is to break the supply line and...
  17. kellys_eye

    VREF pin - LEM HLSR Series Current Sensor

    Looks like Vref is a 'requirement' whether you want it or not as it is used to calibrate the output. Suitable volt-drop resistor combination across the supply line and with a multi-turn preset to set.
  18. kellys_eye

    Reading from 4 identical sensors using a Raspberry Pi...

    You can use two digital ports to drive a 2-4 line encoder and select each device from the encoder output. Saves on two ports if that's a particular issue for you.
  19. kellys_eye

    Relay to turn off power instead of on.

    I should have said SPDT - SIngle Pole Double Throw (also known as a change-over contact). Sorry about that.
  20. kellys_eye

    Surface Mount Part Identification - TC

    Could be that the capacitor being 6.3V (intended for a 5V input max) blew its guts due to the 12V application. Sure the 12V was the same polarity as the 5V though.... probably was but worth checking.
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