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  1. M

    Li-Ion battery: Too much voltage?

    I have a Minn Kota trolling motor. I'd thought that Li-Ion batteries were too expensive, but I see that I can make them out of individual cells for a reasonable cost. The problem is, I think that they put out too much voltage. My trolling motor is straight forward, but I've made a pulse width...
  2. M

    Deep Cycle battery and trolling motor question

    Hey, Part 1 When running a deep cycle battery, I know that current draw can be used to calculate run time as a factor of Amp Hours of a battery. I also know that batteries should only be drained down to about 50%. So, if I'm running a trolling motor, should I calculate run time assuming that I...
  3. M

    100V motor on a pump?

    Looking at a pump, it has a 4-pin connector. It's rated for 100V, 50/60 Hz, .15/.17 A, 5W. Considering the frequency rating, it seems like this is an AC pump. Considering that the voltage is "100" rather than "115" or "120", and considering the 4-pin connector, it seems like this is a DC...
  4. M

    Back up power for small load, extended run time

    I need to run several devices (a heater and a few pumps) for an aquarium, more-or-less constantly, in the event of a power failure. The total consumption of these devices, is about 50 watts per hour. I'd like to implement a backup system that, ideally, will run on external AGM batteries, so...
  5. M

    Lamp: Will it burn my house down and kill me?

    I'm looking at this UV sterilizing lamp (link at end of post). The bulbs will be contained within a metal duct, but the ballast will be outside of it. I can't find any manufacturer information regarding it. Is it a realistic worry that this might catch fire and burn my house down? Similar...
  6. M

    A/C device becomes active when other becomes inactive

    Let's say that I want to run an A/C device. If it should fail, I'd like a backup A/C device to turn on to take the place of the first. This seems like it would be a really easy circuit to build, and perhaps something is already offered that does this. Can anyone point me in the right...
  7. M

    I need to hire someone for a logic design

    I'm building a project that will require at least one, and maybe two, automated processes involving logic circuits and a DC power source (with a wall wart) with a battery backup. It(they) will be simple, but are beyond my capabilities. If anyone is interested, PM me. Thanks.
  8. M

    incorrect load on soldering iron transformer?

    I have read a fair amount about vacuum tube amplifiers. One thing that is of importance in such devices is having a proper load hooked to the transformer. If the impedance is wrong, there is no speaker hooked up, etc., the transformer can be seriously damaged. Which makes me wonder about my...
  9. M

    can I use this wire?

    Hi, I'm wiring up two motors for an automatic fish feeder for an aquarium. Given the nature of the project, the device will frequently see use while not attended. Therefore, it is vitally important that it not catch fire. The motor that draws more current has a stall current of 800 mA, with...
  10. M

    measure current drawn while using pulse width modulator?

    I have a motor hooked up to a pulse width modulator. How would I measure current draw at partial duty? At 100%, it's easy enough. I don't have an oscilloscope, so I can't determine the pulse width at a given setting. If I am at a duty percentage less than 100%, and I take a current reading...
  11. M

    Ratings for AC vs DC devices

    If an AC device is rated for a certain voltage and amperage, can these ratings be assumed to hold true for DC devices as well? What about vice versa? E.g., if an AC plug is rated for "x" amps, could the rating of "x" amps be considered to hold true in DC applications as well? Thanks.
  12. M

    AC plug for DC purpose?

    I have a trolling motor to which I'm hooking up a Pulse Width Modulator. I have installed plugs meant for DC purposes, but am not happy with them. These plugs use a solder connection to wire, which has failed twice already. I'd rather screw a wire down than solder it. Furthermore, the plugs...
  13. M

    need a switch that will deactivate with man overboard

    I have a trolling motor hooked up to a canoe. I need a "dead man's switch" to de-energize the motor if I should fall overboard. This isn't being hooked to the power supply, but rather to a PWM, so current and voltage are low. I have a reed switch, but see a disadvantage: to make it work, I...
  14. M

    Two potentiometers on a pulse width modulator

    I have a pulse width modulator with a dual-ganged potentiometer. I've seen other PWMs with two potentiometers, rather than the single dual-ganged. What two parameters are controlled by the potentiometers? I'm using mine on a trolling motor. If I were to decouple the parameters by using two...
  15. M

    waterproof dual-gang potentiometer?

    I've been looking for a waterproof (or at least splash-proof) dual-gang potentiometer and have not had any luck. Ideally, it would be 100K, but this isn't an absolute requirement. Does such a component exist? Thanks.
  16. M

    protecting leads on a jack?

    I have a barrel jack made by Switchcraft that I intend to mount through the enclosure of a project. Unfortunately, the enclosure will need to be opened for service regularly (it's just the nature of the project). On the inside, as things currently are, I'll have the soldered leads connected to...
  17. M

    Using a DC motor speed controller as an "off" switch?

    I purchased this DC motor speed controller: http://www.amazon.com/gp/product/B00F839VNQ/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 Now, I have another aspect of the project. Here, ideally, I'd have a motor that would be either off or on (with varying speeds). When experimenting with this...
  18. M

    jack/plug type for DC power?

    I'm putting together three projects involving motors that will run off of a 12V "wall wart" power supply. I picked up some radioshack size "M" coaxial connectors. These are cylindrical plugs that go straight into the jacks. I've had problems with these. A jack provided a poor contact, so I...
  19. M

    help with voltage divider

    I'm building a simple circuit based on a 12V DC power supply. I want two motors to run at the same time. One motor is rated for 12V, and the other is rated for 6. I understand that I can have a circuit that runs from the power supply, to a resistor, which leads to another resistor, and...
  20. M

    grounding dc circuits

    I'm making two devices, both of which will run off of "wall warts" providing 12V. I will be running motors, and have fuses that are rated to about 40% stall current. I'm wondering if I need to (should) ground the DC supply in relation to the device housing. In the first case, I will be trying...
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