Search results

Search Forums New Posts
  1. BGB

    projects: testing this out...

    BGB submitted a new Showcase Item: projects: testing this out... Read more about this showcase item here...
  2. projects: testing this out...

    projects: testing this out...

    so, current projects for stuff I am working, or have built: QuadRotor / RoboWasp: * Approx footprint: 1.25 meter (4 feet). * Approx weight estimate: 15-25 lbs * Estimated max thrust: 56 lbs (at 480 watt, or 12v 40amp) * Power Source: Have a 9Ah (24Ahr) LiFePO4 battery. * Bulk Construction...
  3. BGB

    Replacement for TIP120 Transistor

    if current requirements are low enough (below 25 volt and 1.2 amps), maybe something like a 2N3506 (TO-92 NPN Darlington) could also work?... maybe also the 2N6426 which is 40 volt 1.2 amp. these could be closer to a drop-in replacement, and use smaller (TO-92) packaging. MOSFETs may or may...
  4. BGB

    Best solder to use

    I like to crimp and then solder, as the soldering basically makes sure the crimp doesn't come off (say, if the wire is pulled on or similar), but sadly doesn't work well for very small connectors (where basically the solder may flow into and fill up the connector). for the heavy wires, the type...
  5. BGB

    Best solder to use

    my experiences: 60/40 SnPb (Tin/Lead) solder: good for soldering electronics. SnAg (Tin/Silver) solder: works if one doesn't have anything else, hassle to use, doesn't wet well, kind of makes a mess. I have a few boards mostly soldered using this stuff. in general though, I much prefer 60/40...
  6. BGB

    Old RS-232 compatibility with new computers?

    or maybe they are not setting the baud rate and format correctly? unlike with newer interfaces, RS-232 needs to have both ends match in terms of baud-rate, number of data/parity/stop bits, ... in order to work. most devices I have seen are 8N1 or sometimes 7N1, but baud rate is rather variable...
  7. BGB

    Recommendations for DC Motor and Motor Couplings Pair

    no specific answers, but: figure out about what you need (if you only need to turn it on/off, probably a gear-motor will work, just figure out about how much torque you need and similar and go looking around for something affordable...). torque needed to open/close the valve will probably...
  8. BGB

    Solar Panels for Hydrogen?

    reminds me of a random idea I was more thinking like a turbojet (IOW: more like the engine in a fighter jet), where the goal is to have high exhaust speed and high thrust from a comparably small engine. for a turbofan (like in a typical commercial aircraft), one almost may as well just use a...
  9. BGB

    Solar Panels for Hydrogen?

    reminds me of a random some ideas I had had before, but thus far still purely speculative, would be ways of combining ducted-fan with ion-engine technology to allow for a possibly much smaller and more powerful electric thruster (for terrestrial use). one possible variation could be using a...
  10. BGB

    Need opinions on regulation.

    yeah, I think a typing error... in my case, the power efficiency isn't really a big issue, at least vs the annoyance of needing a cooling fan taking up space and being in the way (also sort of needed for the H-bridge transistors though). this is because, at around 750mA, it is a pretty small...
  11. BGB

    Need opinions on regulation.

    yeah. just 750mA seemed like not a lot of power, and the things are rated for 1.5A, ... the first one I tried using was a straight clay heatsink, but as it got a little bigger I noticed that it didn't get hot uniformly (some parts got hot, others were still cool, and generally was a pretty big...
  12. BGB

    Need opinions on regulation.

    FWIW: I have been using 7805's and have been having a different issue (going from around 12-14v): they get hot during use, and then go into thermal shutdown when they get too hot. I have basically made them work with big gobs of metal-dust mixed with clay gobbed on as a heatsink and blowing on...
  13. BGB

    idle: yet another current-limiting scenario...

    left out (kind of the original), but also considered, would be per-motor current limiting circuits, or possibly small series resistors (such as 0.2 ohm, likely made from a segment of welding-wire or similar), possibly in addition to the use of fuses. or, maybe using a nail as a shunt resistor...
  14. BGB

    idle: yet another current-limiting scenario...

    ok, here is the scenario this time: I am still using ADRS-550SH motors, for another thing this time. some stats for the motors: Operating voltage: 3-16V No load speed (min.): 19,000rpm No load current: 1.4A Stall current*: 74A Max. efficiency current: 10A Max. efficiency...
  15. BGB

    Sealed Lead Acid Batteries

    yeah, lead-acid batteries are sort of annoying in some ways. hadn't been that precise, just noting that after a little while current draw gets pretty low. 0.7% C seems about 0.06A. the batteries like to hang out for a while at around 1% though. though, there are a lot of tradeoffs between...
  16. BGB

    Sealed Lead Acid Batteries

    in my case, I am charging lead-acid (UPS style, AGM/VRLA) batteries using a variable power supply (for powering some current battery-powered projects). I have noted that even in the "Small/AGM" mode on an automatic charger, it gives behavior that doesn't seem quite right (such as trying to...
  17. BGB

    battery powered device, reviving some old UPS batteries...

    status: several days of intermittent charging and some cycling. can get around 2A for several minutes from the battery... box-robot needs around 5A to move both motors... yeah, these batteries, not so good... I estimate they are operating at around 1% to 2% capacity. may try to get some other...
  18. BGB

    battery powered device, reviving some old UPS batteries...

    well, I am building a battery powered device (a small/modest-sized rolling robot, around 15x17 inches, or 30x34cm, with mostly cardboard construction), seemingly relatively low power (around 10A max), and had a few old/used UPS batteries (lead-acid, 7.0Ah, AGM/VRLA style). don't know full...
  19. BGB

    LPC21xx Microcontrollers

    I had done stuff using PDM, which is "sort of like PWM, but slightly different". I am not sure if they are entirely interchangeable, as I suspect there may be cases where the receiving end expects a particular modulation, as opposed to a specific duty cycle. I have also noted that there are...
  20. BGB

    Electric motor connections

    I did mess up a minor detail though, in that BLDC motors need 3x or 4x half-bridges, not H-bridges. a dual H-bridge driver should be usable for running them though (for low-power motors). but, yeah, in terms of what they can do, they are very different. ( decided to refrain from going down a...
Top