Digi-Key TechXchange Communities : Discussion List - Projects and Designs

Remote switch & white LEDs

noreply@digikey.com — Fri, 10 Feb 2012 15:23:35 GMT

Sorry, this is actually two questions.

Question 1. I have a model train that has LED lighting in the cars. The lights are activated by waving a magnetic wand over one end of the car.

Took one car apart and found a magnetic reed switch, some sort of an IC (three lead, SMD potted in epoxy) and 2 - 1.5V batteries as the only components on the circuit board (besides the LEDs - no resistors, no capacitors, no nuthin!).

Since I broke the glass reed switch taking the board out, I have obtained replacements (100V, 1A), soldered one in and it works fine. Trouble is, the IC is potted with dark green epoxy so I can't tell what it is. I know if I scrape off the epoxy I will probably destroy the printing on the IC.

I think it may be a low-voltage SCR, but am not sure. It obviously acts as a latch since the reed switch is normally open except when the magnet pulses it, which grounds one lead of the IC to the negative pole of the batteries for a short time and the LEDs go on. When you pass the magnet over it again, the lights go off. This works much better than any other kind of switch since it is hidden inside the car (nothing shows outside).

Any ideas as to what the potted component is? (All the latching IC I have found are low-current CMOS Hall-effect ICs - don't think they would be able to drive two high-intensity LEDs). I would like to order replacements for that IC (either SMD or through-hole), since I am bound to screw one up eventually and the manufacturer isn't forthcoming with part numbers (not surprising).

Second question. I am looking for warm white LEDs in 3mm TO-1 size (through hole mount). LEDtronics makes exactly what I am looking for, but I don't want to order lots of 500, 1,000 or more!!! (Digi-Key doesn't stock them, either).

The color I am looking for is around 3,000K or slightly below. Ordered some 4,000K white LEDs from DigiKey (special order - still waiting) but think they might end up being too cool (and cost around $1 each). Any suggestions??? I want an LED that looks like an incadescent light color-wise.

-- John

Is it possible to build a home-made Tesla Coil?

noreply@digikey.com — Fri, 17 May 2013 16:43:05 GMT

If my understanding is correct, one needs to have a firm grasp of alternating current, inductors, capacitors, and the concept of resonant circuits and be able to use software (Tesla coil simulator) to simplify the actual calculations.

Assuming I were to begin by with a spark gap coil design (as it’s the simplest in theory), what is the best type of transformer to charge the primary tank capacitor?

Is a solid-state type easier for the first timer to tackle?

Thanks,
Zigg

IF DESIGN RESOURCES

noreply@digikey.com — Fri, 17 May 2013 02:05:02 GMT

I want to design a two or three state 455 kHz IF amplifier. I cannot find any information relating to IF design, and the selection if IF transformers. I'm not designing an AM Radio, but I have a specific design that would make great use of a few stages of IF... Any resources you know of?????

Apprendre les bases du protocole TCP/IP embarqué : modules de formation gratuits en ligne

noreply@digikey.com — Wed, 15 May 2013 19:47:58 GMT

Vous souhaitez ajouter la connectivité ethernet ou WiFi à vos produits ?

Les bases du protocole TCP/IP sont enseignées au travers de 5 modules de formation en ligne gratuits (en anglais) :

TCP-IP Intro Part 1: Local Network and TCP-IP Communication

TCP-IP Intro Part 2: TCP-IP 5 Layer Model and Applications

TCP-IP Intro Part 3: TCP-IP Client Server Model

TCP-IP Intro Part 4: TCP-IP Sockets and Ports

TCP-IP Intro Part 5: Local Network and Internet TCP-IP Communication

Vous souhaitez aller plus loin ?

Les formations présentielles Microchip permettent de mettre en pratique dans le contexte embarqué les notions abordées dans les modules de formations en ligne.

La formation COM4201 (webserveur embarqué) est proposée régulièrement dans notre centre de formation et plus rarement en province.

Planning et inscriptions : http://www.microchip.com/RTC

Catalogue des formations ci-joint

230v water heater element control

noreply@digikey.com — Sat, 04 May 2013 21:24:34 GMT

I am currently working on a project that requires a controller for a standard 230v water heater element.

I am open to any suggestions on the most economical way to accomplish this as my knowledge in this area is very limited.

Feedback is external to this controller and adjusted only by the operator.

I'm looking for suggestions on everything from the enclosure to the components to use inside of the unit.

Any suggestions or advice would be greatly appreciated.

Information For An Obsolete Flow Meter

noreply@digikey.com — Fri, 22 Feb 2013 01:06:09 GMT

I have a flow meter made by Osmonics Phoenix Operations.

Model 491

Serial # 3A774603

i don't have a manual for it

the company does't exist anymore.

Its currently programed to read a 3/4" propeller water meter.

i need to reprogram it for a 2" water line.

i would appreciate help from anybody who knows anything regarding this device.

i really would like to get my hands on a manual for it.

Microcontroller to build "smart dumbwatch"

noreply@digikey.com — Fri, 03 May 2013 06:16:40 GMT

Hi there all!

I have this idea of a project but I am brand new at this stuff so I don't really have any real idea how to start! Basically, what I am looking to do is modify an analog watch by adding an RGB LED in it, then have it controlled by an app (which I will have to program) on my Android via Bluetooth, so it would, for example, blink when I get notifications. An extra added functionality that would be awesome if possible is if I could have buttons on the side to control music.

It would be best if it was very low powered so it only needed to run off a watch battery if that is even possible.

Now, I am a complete noobie. Should I use a microcontroller for this? If so, would you have any suggestions as to which one?

Also, would you be able to point me in the right direction on how to learn more about them? I've searched a bit but because I'm so new to this, I think I just don't know where the proper places to look are.

I am fairly electrically savvy (I'm actually a second-year computer and electrical engineering student) but I haven't attempted anything like this before! I hope you will be able to help me out! And if you need me to be more clear on anything, let me know .

Thanks!

RLC values of ceiling fan,light

noreply@digikey.com — Mon, 11 Feb 2013 04:42:03 GMT

pleasse help me to find out the valuse of resistance,inductane,capacitance value of ceiling fan, fluorescent lamp,cfl bulb. i need the approximate values of the above.

SPST rocker switch with reversed LED

noreply@digikey.com — Wed, 24 Apr 2013 00:27:33 GMT

I'm looking for an SPST rocker switch that has an LED indicator, but with a twist. I want the LED to light up when the circuit is DISCONNECTED. So, circuit open, LED is on. Circuit closed, LED is off.

I've previously used Digi-Key part # 67-1933-ND and modified the internal circuit to accomplish the reversed indicator light but that part is no longer available here and it is a hassle to customize anyway.

Does anyone have a suggestion for a replacement switch that has this backwards configuration?

Optical smoke chamber

noreply@digikey.com — Thu, 26 Jul 2012 08:43:27 GMT

Hi,

I am looking for a "stand alone" optical smoke chamber - there are plenty of smoke detector ICs or fully equipped smoke sensor modules with a relay output, but I can't find a smoke chambers anywhere!?

Any ideas?

Thanks,

Roman

How can I find the traces I need ?

noreply@digikey.com — Wed, 17 Apr 2013 18:53:04 GMT

I am trying to make a calculator into a counter. I have the calculator and reed switch.

My problem is I can not find the traces that go to the equal button. I am not a tech but I have been asked to do this at work and I would like to make it happen.

I am using a ti 1795 sv calculator. All the traces are on the bottom with the push buttons on top. How do I go about finding the two traces I need ?