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  1. (*steve*)

    Replace 9Volt Battery with Solar Panel

    The simplest solution is to use a battery technology that will cope with float charging. Lead acid and lithium batteries tend to fall into this category, but both require some battery management. Whilst there are ways of doing this relatively simply, it's still relatively complex compared to...
  2. (*steve*)

    BMS for Lithium Iron phosphate battery bank LiFePo4

    Connecting the charger that way will stop charging as soon as one battery reaches capacity. Three other issue you need to check carefully is what happens when these are connected in series to power a load and one BMS decides that it's batteries are dead. This will place a reverse voltage...
  3. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    Oh silly me. I had filters turned on. When I turned them off, the difference between the magnitudes fell from 6% to 0.4%.
  4. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    Woo hoo! It certainly seems to work. The functions of the SR530 and the 5210 are very similar. Hey, they were manufactured probably in the same year so it's probably a similar "state of the art". The 5210 has 2 LCD displays and one analogue meter. I'm pretty sure it can display the same...
  5. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    All our back together. Pretty! Now what happens when we apply power? That looks well behaved. Previously the two LCD displays showed ever-changing values and the meter swung back and forth until the device locked up and everything froze. At the moment everything is stable until you...
  6. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    That seems to fix the +/-18V rails. They now measure +17.6 and -18.2. Shiny new resistor And the tantalum has blown up! I replaced the 1μF 25V with a new 10μF 50V. Now let's put it back together and see what happens.
  7. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    Damn, my local electronics store has morphed into Tandy electronics! Anyone want to guess at the cost of labour and packaging vs the cost of the resistors?
  8. (*steve*)

    Capacitive reactance affecting voltage divider output

    Let me guess. The device is a piezoelectric alarm module (like a sonalert). It has three wires. Two are connected to power and the third is a logic input used to turn the alarm on and off. I love these guessing games.
  9. (*steve*)

    ebike with speaker amp as a watt amperage is it possible

    @tony.sax I would encourage you to ask the questions on an electric vehicle forum. I was an active member of one for a while, I think it was called "endless sphere" or something similar. They had dedicated groups for small vehicles such as yours. You'll find people with expertise specific to...
  10. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    I hope you guys don't think I'm a one trick pony.
  11. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    Removing that board and the other half of the shield wasn't too hard. There's only two 18V regulators there, and they're not connected to much of a heatsink. But that looks odd. I'm not happy with that resistor. It measured about 18Ω until it fell apart. Oops! Well it's an open...
  12. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    I've removed the board that I think is the second channel (that's the main difference between the models 5209 (single channel) and 5210 (dual channel). And removing that allowed me to take the cover off the large shield. Look at all them tantalums! It looks like I can unplug everything...
  13. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    The mains transformer has 2 windings. An 8VAC and a 48V CT winding. There is only a little over 1A being drawn from the 8VAC winding. However, the 48VAC CT winding seems to be providing 1.7A. That seems excessive. All of the logic I've noticed is CMOS (HC and HCT). The processor is a...
  14. (*steve*)

    Zero ohm resistors.

    I don't buy that. I think I'm with you @shrtrnd. Is there an HP Journal article on the use of zero ohm resistors for board protection? :-)
  15. (*steve*)

    Rehashing Info About Surface Mount Resistor Size

    Yeah, I think the a problem when your vendor starts making decisions about what you want
  16. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    And guess what, when turned on, I get some probably odd readings which change for a while then freeze. And... The transformer smells a bit. Yep, I did change the line voltage. A bit more information, this was manufactured in Sept 23, 1988. The unit draws 350mA and the fuse is a 500mA slow...
  17. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    Following the DTIOTIA principle, here's a look inside: Oooh, look, a piece of paper that's been removed and replaced again. I wonder what it says...? Looks like configuration info. That might be useful! I can see at least 6 tantalum caps. At the moment I can't read the expressions on...
  18. (*steve*)

    EG&G PAR 5210 Lock-in amplifier repair

    Ok, no guessing games this time. It's a Princeton Applied Research model 5210 Lock-in amplifier. Coming from the same source (a calibration and repair facility) so I'll assume it's BER even though the description didn't say so. (If it's not, I'll sadly move this thread somewhere else)...
  19. (*steve*)

    What makes a successful engineer?

    Perfectly true. As long as the role doesn't involve actual engineering.
  20. (*steve*)

    Any ESP8266 WiFi Experts here?

    The esp8266 modules in their native state are essentially rs232 extenders. In this case you can use them just as the manufacturer originally intended. They have an "AT" command set for setting them up.
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