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  1. Old Steve

    LED Circuit not behaving as it should

    Ah, I was going to ask what the 9410's Vgg pin was connected to. A programming voltage perhaps, although a negative programming voltage seems odd. Maybe not though, I'm only really familiar with PICs in that regard. They use a higher positive voltage for programming.
  2. Old Steve

    System reset circuit help please

    It could also be a protection mechanism, 'in case' both went high.
  3. Old Steve

    System reset circuit help please

    It could be that only one or the other is usually high, and that tying the reset to both going high was just a simple way to achieve a reset without additional circuitry.
  4. Old Steve

    Mind & Infra Red Controlled Robot Car

    I'm looking forward to seeing how you progress on this. When the budget allows, I might well buy a Mattel headset too, and have a bit of a play. I'd never heard of them until I saw this thread, then did a bit of extra reading. ('Mind-control' - I thought you were dreaming! :rolleyes:) I'd...
  5. Old Steve

    Home made speaker

    What is the current rating of the transistors? Their gain should be fine. I built a very small amp for a door chime circuit the other day, and used an SS8050 NPN and SS8550 PNP complementary pair bought from RS components. If you can get them easily, they'll work nicely in your circuit.
  6. Old Steve

    Not getting correct voltage from voltage regulator

    Try an LP2950. A 2.2uF output cap is recommended for the 3V, 3.3V versions and 1uF for the 5V version. I accidentally left out the output cap on an LP2950-3.3 a few weeks ago, (or I might have put a small 0.1uF cap on it, I forget), and the output was high according to my DMM. I added a 10uF...
  7. Old Steve

    Light Ignition Circuit?????

    That was a quote from the datasheet - it knows a lot. :D
  8. Old Steve

    Light Ignition Circuit?????

    Every AC cycle, since the current reverses each time. To quote the datasheet again "the trans-former generates high voltage pulses across the lamp"
  9. Old Steve

    button device and buzzer

    To avoid placing the buzzer directly across the 1K resistor, a DPST pushbutton switch could be used instead of the SPST pushbutton shown in the drawing. The second pair of contacts on the DPST pushbutton switch could then operate the buzzer completely independently of the main circuit. Having...
  10. Old Steve

    Finding replacement for legacy Motorola Gate chip

    It'd be nice, wouldn't it? Give it a few years and who knows...... I guess another option would be a few pins sticking out of the top for programming, that could be cut off afterwards.
  11. Old Steve

    Finding replacement for legacy Motorola Gate chip

    Programmable logic has been around for a long time, (PLDs). Unfortunately, though, there's no way to make the programmed chip pin-compatible with an equivalent fixed-logic chip. rbrooks, why not just buy from China or Hong Kong? A little expensive at $6 + delivery, but it'll get you up and...
  12. Old Steve

    Not getting correct voltage from voltage regulator

    Don't forget those bypass capacitors, too. Some regulators won't work without them. (The LP2950 and similar MUST have an output capacitor.) Incidentally, if you're using a plug-in breadboard, a regulator fits OK in the holes without needing to use flying leads. (Excuse the dirty, dusty old...
  13. Old Steve

    Light Ignition Circuit?????

    The 'functional diagram' from the datasheet helps clarify more, too:-
  14. Old Steve

    Light Ignition Circuit?????

    The datasheet explains it clearly:- "When the peak voltage across C1 reaches the break over voltage VBO of the LIC01, this device turns on and produces a pulse of current through the primary of the transformer. In turn, the trans- former generates high voltage pulses across the lamp."...
  15. Old Steve

    Not getting correct voltage from voltage regulator

    Here's a link to the 7815 at Altronics:- http://www.altronics.com.au/p/z0512-7815-15v-1-amp-to-220-fixed-voltage-regulator/ I'll get a copy of the datasheet and upload it in a couple of minutes..... Well, I tried, but got an error that it's too large. Instead, here's a link to the datasheet:-...
  16. Old Steve

    Not getting correct voltage from voltage regulator

    Do you have a link to the eBay listing? What you appear to be getting is a forward voltage drop equal to that of two series diodes, rather than a regulator. How do you know which way to connect them, too, without numbering and/or a datasheet? A photo of these 'regulators' might clear things up...
  17. Old Steve

    Not getting correct voltage from voltage regulator

    What type of regulator? A part number would help. The fact that you're getting 25.3V out regardless of whether you use a 5V, 9V or 15V regulator is odd, to say the least. It's also a good idea to put bypass capacitors from the input and output to ground, as close as possible to the pins...
  18. Old Steve

    Mind & Infra Red Controlled Robot Car

    Have you done any basic testing yet, or do you plan to just dive straight in with the car? (You've piqued my curiosity.)
  19. Old Steve

    Wanted: DSC part # PC5192

    This is pretty late, but did you try contacting DSC? And is it a 5921, rather than 5192? I couldn't see a 5192 on their site. http://www.dsc.com/alarm-security-products/PC4936/PC4937%20-%20PC4936/PC4937/887
  20. Old Steve

    RF controller relay help

    I was wondering what it will be used for, too. It sounds a lot like the water supply for a small hydro-electric setup. Regarding controlling the gate to stop in different positions, a crude method would be to drop all of the automated stuff and just have the gate keep closing while the button...
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