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  1. kellys_eye

    Can't find the transformer I need so need to build my own

    Well that eases my mind somewhat! Here's me thinking they were the plastic shrink-wrapped things you stuff in a drone! Looks more like a 'battery wall' type device. 1C seems awfully high rate to charge - not in an electrical sense but in a 'why the heck would you want to' sort of way, not to...
  2. kellys_eye

    Need help desoldering

    Many such connectors have larger solder areas that offer mechanical support to the part (as opposed to the electrical connections) which, as mentioned, can be attached via other board layers) which go to suck heat away from the part when trying to remove them. Frustrating. But the best method...
  3. kellys_eye

    My first circuit is a bit advanced (H-bridge!)

    They are actually 1W transistors. You need to know the motor current and the Vce(sat) - up to 0.5V on one of the types - to determine the max power dissipated in the transistor when fully saturated (i.e. on). Back EMF is an issue but the diodes you have will cope more than adequately. Show us...
  4. kellys_eye

    What are these?

    Yep, most likely an IR receiver - I recognised it from the description!
  5. kellys_eye

    Can't find the transformer I need so need to build my own

    I'm not sure with LiFePO4 cells but charging them at 140A seems somewhat excessive - is this not the maximum discharge current? Can you provide a link to the actual battery being used or some data regarding its manufacture?
  6. kellys_eye

    Transformer to build 12 volt battery charger

    :lol: - I have no idea why that showed up on the list of 'new posts' I usually click on. I didn't even notice the date!
  7. kellys_eye

    Vizio 55 iinch LED 4K TV

    Surprisingly this could be a simple case of 'dirt'. The large plastic sheets used as diffusers for the backlight are prone to developing a static electric charge which attracts dust to such an extent that patches of darkness can appear. The other (obvious) reason is LED failure - which can be...
  8. kellys_eye

    Grounding question in regards to battery powered inverters.

    Depends. Is the output fully floating or referenced to ground (earth)? Are you measuring under ideal load conditions? The spec for waveform distortion will be optimised for a specific load (I suspect). Does the output vary under constant load? (not good - points to simple poor regulation in...
  9. kellys_eye

    Can't find the transformer I need so need to build my own

    What I am suggesting are a few simple ways to achieve what you require. Your own idea to make a transformer is, in my opinion, far too involved. The easiest way to get a high current source is from suitable BATTERIES and lead-acid (i.e. car batteries) are cheap, plentiful, easy to recharge and...
  10. kellys_eye

    Transformer to build 12 volt battery charger

    Using a 'simple' transformer/charger unit is a sure way to shorten battery life. You need a properly regulated and conditioning charger and it doesn't need to be 'multiple amps' either. Since you're alongside and the vessel is being unused for long periods the rate of charge can be relatively...
  11. kellys_eye

    Can't find the transformer I need so need to build my own

    The 'lead-acid' charger will be anything suited to the battery you use as the SOURCE supply. You can purchase any number of lead-acid battery chargers for different purposes. The key is that the charger only outputs a low current and requires the appropriate time to charge the battery to its...
  12. kellys_eye

    Can't find the transformer I need so need to build my own

    Forget using a transformer. Get a decent lead-acid battery and charger. It will be able to dump 100's of amps into any load you care to attach and regulating from 12V to your desired output is easy-peasy at 12V rather than from some obscure AC source. If you want to use SMPS you can obtain 5V...
  13. kellys_eye

    A few questions about the allocation of frequencies

    'Not allocated' means (imho) that there are no current rules/regulations pertaining to the use of it. Governments (apparently) 'own' the airwaves and 'sell' licencing to those who want to use specific parts of it. If that 'un-allocated' band became popular for whatever reason you can guarantee...
  14. kellys_eye

    For Sale: Various Test Equipment

    Hi and welcome. I'm also UK based so would be interested in seeing a list of stuff and/or pics. cheers
  15. kellys_eye

    How do I minimize/prevent AND recover from burnout from studying?

    Can you take the course credits across to another specialisation? How far are you in to the degree? The whole point of advanced education is to both extend your abilities and to discover the LIMITATION of your abilities. You seem to be coming up to the latter. It does neither yourself nor...
  16. kellys_eye

    How do I minimize/prevent AND recover from burnout from studying?

    Stop the meds. They are not the answer nor are they a solution. If you aren't UNDERSTANDING the subject there is no amount of study going to make that happen. By 'understanding' I mean - do you know the subject well enough to be able to teach it to someone else? And I don't simply mean...
  17. kellys_eye

    Portable Computers

    The only comms I want to fully disable is the phone side. I have reservations on the software being able to do that - same goes with just removing the SIM card - and certainly 'airplane' mode won't cut it. Even removing the antenna isn't good enough - you can probably still operate the device...
  18. kellys_eye

    Portable Computers

    Years ago, portable computers were called PDA's (Personal Digital Assistants) and the best you could get was, by today's comparative market, very poorly powered and had a screen of VGA quality at best. I realise that mobile phones have taken their place (let's not discuss tablet PCs here - bear...
  19. kellys_eye

    220-230v 3.6kw EU to uk appliance

    In the UK you would have to have the device wired to a wallplate with a double-pole isolation switch. Fusing would be at the consumer unit - such high power devices are usually wired to their own circuit breaker. You cannot (reasonably) attach a plug although a 16A commercial plug/socket COULD...
  20. kellys_eye

    DIY battery charger generator: Confusing problems with the alternator, it's not charging.

    Running the alternator WITHOUT a battery will cause alternator regulator failure. If you have more than 2000rpm at the alternator it should charge - is the battery in NEED of a charge?
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