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Re: basic question regarding wiring connections

 by davep238 ¦  Sun Mar 12, 2017 9:00 am ¦  Forum: Projects ¦  Topic: basic question regarding wiring connections ¦  Replies: 2 ¦  Views: 670

The dimmer won't work. Instead, you need a 12 volt power supply. They are listed in "Customers who bought this item also bought".

Re: Newb + Truck Bed LED question

 by davep238 ¦  Sun Mar 12, 2017 8:39 am ¦  Forum: Projects ¦  Topic: Newb + Truck Bed LED question ¦  Replies: 1 ¦  Views: 633

LEDs are NOT a short circuit when the threshold voltage is reached. Instead, like all diodes, they have a forward voltage drop (Vf). For white LEDs this is 3.2 volts to 3.5 volts. In this case, I suspect that the LEDs are in parallel, and not in series. LED current must be limited, or the LED will b...

Re: Layer 117 was not listed in eagle.

 by davep238 ¦  Thu Jan 26, 2017 7:33 am ¦  Forum: PCB Design Questions ¦  Topic: Layer 117 was not listed in eagle. ¦  Replies: 1 ¦  Views: 1136

On the command line enter:
layer 117 a_name_for_this_layer
then it will show up in the listed layers. This information is available by entering HELP LAYER in the command line.

Re: RS232 Shifter SMD LED removal?

 by davep238 ¦  Sun Jan 22, 2017 7:01 am ¦  Forum: SparkFun Product Questions ¦  Topic: RS232 Shifter SMD LED removal? ¦  Replies: 2 ¦  Views: 391

Go ahead and remove the LEDs. It won't hurt.

Re: Relays needed in the PCB design for my smart car

 by davep238 ¦  Tue Jan 10, 2017 8:10 am ¦  Forum: PCB Design Questions ¦  Topic: Relays needed in the PCB design for my smart car ¦  Replies: 7 ¦  Views: 1500

Hello I am in the process of designing a PCB that incorporates a microcontroller, LEDs, capacitive sensors and relays to control light in my smart car. I have taken this picture as my reference.I have the little stuff worked out and have it prototyped and working, but I want some outside input on t...

Re: Bread board leads to power

 by davep238 ¦  Thu Jan 05, 2017 6:22 am ¦  Forum: Arduino ¦  Topic: Bread board leads to power ¦  Replies: 3 ¦  Views: 578

Are the breadboards the thick white plastic ones with the square holes? (Please show us a picture of your breadboard) If so, then you can use plug your parts directly into the holes and use #22 solid wire to connect them. There are long conducting strips that run the length of the breadboard, usuall...

Re: Adjusting LED current

 by davep238 ¦  Wed Jan 04, 2017 7:41 am ¦  Forum: Projects ¦  Topic: Adjusting LED current ¦  Replies: 5 ¦  Views: 673

Have you tried not using the CC regulator, and instead connecting a resistor in series with the LED to the output of the buck regulator? The resistor will turn the constant voltage into a constant current.
BTW, the battery only puts out 17.6 watts, so 3 watts is a lot of power.

Re: Is it safe to use a SPDT relay as a SPST relay (110v)?

 by davep238 ¦  Wed Jan 04, 2017 7:33 am ¦  Forum: Projects ¦  Topic: Is it safe to use a SPDT relay as a SPST relay (110v)? ¦  Replies: 2 ¦  Views: 527

Greetings. I'm a beginner and I'm trying to build a very simple arduino-controlled switched 110v outlet. I thought I could use the JZC-11F relay ( that comes with the SparkFun kit, but I now realize that it is a SPDT relay. I only want the outlet to turn on and...

Re: LED wiring

 by davep238 ¦  Tue Jan 03, 2017 7:03 am ¦  Forum: Projects ¦  Topic: LED wiring ¦  Replies: 1 ¦  Views: 537

4.5v / 20 ohm = 225mA per string, or 11.25mA per LED. I suppose they are wired in parallel. 4 strings x 225ma/string = 900mA total. So a 1 Amp adapter would work. If you used a 5v adapter instead of a 4.5v adapter, each string will draw 250mA. So again, a 1A adapter would work.

Re: Transformer ID

 by davep238 ¦  Tue Dec 20, 2016 7:20 am ¦  Forum: PCB Design Questions ¦  Topic: Transformer ID ¦  Replies: 1 ¦  Views: 1005

While I can't figure out the transformer, there is a resistor above the blue relay that appears to be burnt.

Re: Logic Level Converter - Bi-Directional question

 by davep238 ¦  Mon Nov 07, 2016 5:38 am ¦  Forum: PCB Design Questions ¦  Topic: Logic Level Converter - Bi-Directional question ¦  Replies: 2 ¦  Views: 943

On the schematic, notice that ground is connected to each connector. This is also obvious on the PCB if you click on "X" (ratsnest).

Re: How to read pin notation in IC datasheets

 by davep238 ¦  Fri Oct 28, 2016 4:36 am ¦  Forum: Projects ¦  Topic: How to read pin notation in IC datasheets ¦  Replies: 3 ¦  Views: 737

In IC datasheets there are often tables like the following for two format selection pins on a chip, CODE 0 and CODE 1 CODE [1:0] FORMAT 00 Right Justified 01 Left Justified 10 Chip Reset 11 Gated BCLK I am confused about how to read this To get left justified output would I set CODE 0 = 0 and CODE ...

Re: Eagle lib design help

 by davep238 ¦  Wed Oct 26, 2016 8:50 am ¦  Forum: PCB Design Questions ¦  Topic: Eagle lib design help ¦  Replies: 2 ¦  Views: 1065

Hi guys. Can anyone help design a Altera IC lib for me ? There is a 44 pin version in the eagle 6 lib, but I need the 68 pin one. I can't figure out the lib editor it doesn't seem to make any logical sense to me. Or if anyone knows a design service anyone does to create libs then I don't mind sendi...

Re: Can Eagle 7.2 open a 7.6 file?

 by davep238 ¦  Mon Sep 05, 2016 9:05 am ¦  Forum: PCB Design Questions ¦  Topic: Can Eagle 7.2 open a 7.6 file? ¦  Replies: 1 ¦  Views: 771

Eagle 6.6 will open Eagle 7.5 files with a few warnings, so I assume that 7.2 should be able to open 7.6 files.

Re: Optocoupler Circuit Overheating

 by davep238 ¦  Sun Sep 04, 2016 7:53 am ¦  Forum: PCB Design Questions ¦  Topic: Optocoupler Circuit Overheating ¦  Replies: 3 ¦  Views: 1530

The 555 timer's power supply can be up to 16 volts, so why not use a 12 volt regulator (7812) instead of the 5 volt one? The 7812 will dissipate less heat since there will only be a 12 volt drop across it vs 19. A small heat sink would be a good idea too.

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