Search results

  1. S

    Considering viability of project: small wind turbine for 5 V camping charger

    Okay, thanks. Could you tell me whether I'm right in thinking that in the case of a four-phase stepper motor, it's best to get one with eight wires (so no commons) in order to rectify each pair and get the maximum power out of it? It seems to me that if there are common wires, you're losing some...
  2. S

    Considering viability of project: small wind turbine for 5 V camping charger

    This website for example: http://www.reuk.co.uk/Stepper-Motor-Basics.htm but I've seen other websites and YouTube videos suggesting this type of motor for this type of purpose.
  3. S

    Considering viability of project: small wind turbine for 5 V camping charger

    I'm considering making a small wind turbine to charge a 5 V 8000 mAh battery pack. The wind speed in target hills is typically 5-10 m/s. If it ever approached 20 m/s while I was there, I'd probably leave! I think I could use a stepper motor like this combined with a fan blade like this...
  4. S

    Advice for soldering long chain of RGB LEDs

    Hi, thanks for your advice. I'm actually intending to use one of these controllers from China. They seem to output a constant voltage and I was going to use a single high-power resistor (one for each colour) attached to a heatsink. There will be three columns of LEDs in series. I've done a...
  5. S

    Advice for soldering long chain of RGB LEDs

    I have many 5 mm RGB LEDs that I want to solder together into a long chain. I want to make three chains of about 30 cm length. They will be hidden inside some frosted acrylic tubing so it doesn't need to look too pretty but it does need to be pretty straight. In this picture you can see the...
  6. S

    Calculator fault: certain segments aren't showing on LCD

    I have a Sharp EL-506V calculator and certain segments of the LCD figures are not showing. Is there a likely cause for this kind of fault?
  7. S

    Computer PSU failure - voltages low - damage sustained?

    A couple of weeks ago my computer would not boot (the fans all started but the power LED appeared to flicker). I measured some of the PSU (Thermaltake 705w 700 W, now eight years old) voltages and the 12 V output was 10.3 V and the 5 V output was 3.5 V. This is far outside of specification. I...
  8. S

    Electrical generation in power stations - how AC Hz and voltage fluctuates

    I was wondering how power supply characteristics fluctuate with variations in power generation and consumption. In some jurisdictions you can monitor the frequency (Hz) of the national power supply grid(s) and as consumption increases relative to supply the frequency drops. I was wondering...
  9. S

    Connecting USB outlets in parallel for more current draw?

    Yes, it's an electric heater (specifically in an item of clothing I'm making). The heating elements will be lengths of enamelled wire in the arms, legs and torso. The lengths will be calculated and measured to ensure current draw is not excessive.
  10. S

    Connecting USB outlets in parallel for more current draw?

    I want to use a lithium battery pack for a project. This one lets you draw up to 2.4 A, 2 A and 1 A from the different outlets. I would like to know whether I'd have any problem taking the power from each and connecting them in parallel so I could draw a maximum of 5.4 A (I'll avoid approaching...
  11. S

    Request help interpretting LED max Vf spec in spec sheet

    No need for my response? I haven't said anything even remotely offensive. And given that the spec sheet applies to more than one unit, and all the units are not the same, clearly I do have to test my individual unit.
  12. S

    Request help interpretting LED max Vf spec in spec sheet

    No! I want this to make a dynamo-powered light for my bike with a few batteries keeping it lit when I stop at lights.
  13. S

    Two phone batteries in parallel?

    I bought a relatively unpopular phone and therefore there are very few accessories available for it. I'd like to have a battery that can last the entire day on a single charge and so I was wondering whether I can wire in a second battery in parallel to the first. Would they both have to be of...
  14. S

    Request help interpretting LED max Vf spec in spec sheet

    Okay, I'll have to test it. Thanks a lot.
  15. S

    Request help interpretting LED max Vf spec in spec sheet

    This image is a page from a spec sheet for a Philips Luxeon LED. One part of the sheet suggests that the maximum voltage tolerated is 4.95 V. However the LED's maximum tolerated current is 1500 mA and this is reached at 3.85 V. Does this mean that the current remains at 1500 mA between 3.85 V...
  16. S

    Underpowering a RGB LED controller to achieve lower voltage output?

    I have a project for which I'd like to use one of these remote controls and receivers. They accept 12 v and use this to power RGB LEDs on strips. However I don't want to power LEDs on strips; I want to power some RGB LEDs in parallel which means I need to drop the voltage considerably (to...
  17. S

    Advice identifying type of wire and sheath inside hair-curling tongs

    In any case I've burned out the wire and need to purchase a replacement. The original wire is/was not suitable. I need some help finding the right kind of resistance wire though. The original was 4K ohm over a length of 6 cm so I need a wire with a resistance of at least 67K ohm per meter. None...
  18. S

    Advice for buying a 12V 2A adapter?

    I need a 12V 2A adapter for a project and I want to make sure the adapter isn't going to burn my house down (the one I've got here is making fizzing and crackling noises). How can I determine that in advance? Are the particular manufacturer's I can buy from? The project is an LED lamp I've made...
  19. S

    Advice identifying type of wire and sheath inside hair-curling tongs

    This photograph shows the inside of a pair of electric hair-curling tongs. Can anyone advise me what is the purpose and material of the white sheath and what kind of wires is it covering? I'm intent on modifying the tongs by reducing the size of the stainless steel tube which covers the wires (9...
  20. S

    Trying to charge NiCads using a wall wart

    I made my own dynamo-powered bike light with a very simple circuit which charges some NiCad cells to keep the light on when I stop at traffic lights. Due to a disconnected wire, I used it without input which of course drained the cells. I tried to the charge them in this manner once before - by...
Top