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  1. (*steve*)

    G & E Bradley CT471C

    Watch out. Vibration on a meter movement can snap the needle off. Watching that video I felt I was going to see it happen. Of course, you may be nowhere near the resonant frequency, but it can't be doing the needle any good.
  2. (*steve*)

    PCB Design, 12V@N*0.6A, traces, how can i make this work

    You could google for "Trace width calculator" and find a number of on-line calculators. Here is one that allows you to design for temperature rise in the track.
  3. (*steve*)

    One of my colleagues...

    Here is another version of the solder pump, showing several improvements and also highlighting one of the major flaws. This version has two major improvements. Firstly it uses a more powerful geared motor; secondly Ross and I had found a source of (and the existence of) blunt needles. Ross...
  4. (*steve*)

    G & E Bradley CT471C

    Sounds like there may be some issues with some switch contacts.
  5. (*steve*)

    VFD (Variable Frequency Driver) for 3-phase motors.

    Is this what you're after?
  6. (*steve*)

    Frequency response ?

    This abstract and some of the comments following it may be useful.
  7. (*steve*)

    One of my colleagues...

    On with the show... Here is the first of Ross' displacement pumps. I'm pretty sure that this was a very early model because I recognise some of the design issues Ross spoke to me about, and which his later designs addressed. No real attempt has been made to mount a controller on this...
  8. (*steve*)

    Create controlled 50v pulse

    Sorry about not getting back to you earlier. As long as you keep the current to a reasonable value then you'll be fine. However, as a counter example... I accidentally connected a 10W LED to a capacitor that had a voltage across it significantly above the typical Vf of the device. I don't...
  9. (*steve*)

    Can a low side driver control three N-type MOSFETs connected in series?

    Series connected mosfets are occasionally used to switch voltages higher than a single mosfet is capable of. In some cases there are resistors placed across the mosfets to help to equalize the voltage across them, other times the small about of leakage is used for the same purpose. A naive...
  10. (*steve*)

    Fuses - breaking capacity, rupture capacity - fuse resistance

    There breaking current requirement has more to do with the source than the nominal load. As one example, you will find HRC fuses in multimeters that are rated to be used with high energy power sources even though the multimeter itself is never going to draw anything like the breaking current of...
  11. (*steve*)

    Wanted: Oscilloscope purchase.

    200EUR should be sufficient for you to purchase a scope as described in very good condition, possibly with some sort of warranty. It is not much short of what is required to purchase a second hand, but relatively recent entry-grade digital scope with significantly more features (however, I...
  12. (*steve*)

    Dual power supply

    You also have to remember that for a DC current of 100mA, the transformer needs to be rated for 142mA. 15VAC when rectified will give you around 20VDC and that is ideal to be regulated down to 15V. I would recommend a transformer that had a secondary described as either 15-0-15 or 0-15-30 and...
  13. (*steve*)

    One of my colleagues...

    A "Low Current In-circuit Monitor" Ross built a couple of these. At this point I'm not sure if there were design improvements or if he just needed more than one. As usual, the documentation is printed on the outside. The instructions don't specify the power supply voltage, but as Ross was...
  14. (*steve*)

    Greetings to admin

    Hello and welcome to Electronics Point. What does an engineering task manager do, and what brings you here?
  15. (*steve*)

    One of my colleagues...

    I was hoping to get some more detailed photos of those positive displacement solder dispensers, however today got eaten up and so will tomorrow... Here are some gadgets Ross made to easily dispense small quantities of solder paste from the large syringe-type containers. On the top and left...
  16. (*steve*)

    One of my colleagues...

    Wait until you see the pneumatic dispensers! Whilst he made a number of electronically operated versions, Ross also designed a model that is manually operated, works really well, and can *almost* be made at home from a few cheap Chinese products costing a handful of dollars.
  17. (*steve*)

    One of my colleagues...

    Some "Positive displacement solder dispensers" I introduced Ross to surface mount components. He was sold pretty much as soon as he realised he didn't have to drill so many holes in his home-made PCBs. Fairly soon he decided that there had to be a better way of dispensing solder paste than...
  18. (*steve*)

    One of my colleagues...

    The other "Low power load box". There were 2 of these, with different value resistors. This one has 2R2 steps rather than 27R. It looked a little dusty before I cleaned it up. I don't think Ross had used this one in a while. After cleaning up the top a bit... Much nicer! And this...
  19. (*steve*)

    Create controlled 50v pulse

    You should be seeing over 11 volts at the gate. What are you seeing?
  20. (*steve*)

    Create controlled 50v pulse

    The picaxe runs interpreted code, it's a lot slower than native code. Even that doesn't explain how slow the pulseout command is, but other than changing to a different microcontroller (or just a hardware solution) you've got to work with what you've got.
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