wuemura

Yes, the process is very easy, here some photos of my board, so easy and you dont have to try "x" times, just put the board under water and it's done, can't be more easy than this, and is very cheap.

I did my board with cloths Iron also, it took about 2 min to transfer the toner, and like the photos in that link, the design came out perfet.

Thank you audioguru, the 20k resistor it's on the other board. ;)

I've done this today, it works fine, it took me about 30 min to make the board. The pages that i use do not absorve the toner, you can remove from the pages with your fingers if you want to. The transfer process took about 5 minutes, very fast and clean.

The good thing is, it works very well http://myweb.cableone.net/wheedal/pcb.htm

Thank you audioguru, i will build the circuit and i let you know. ;D

I've found this schematic to use as a base: Just need to figure the LDR part.

Hello Audioguru, i've sent you a PM. Scroll down the PDF to see the conection to the LDR! Thanks!

Project files attached below. O2_project.zip

Hello guys, after a few months (problem to find LM3914 around here) i've build the thing, but is not working :( Attached to this message is the full schematic and board design and the Eagle project files. Problems 1- When i turn the device on, the 10th led lit and stay fixed, when i turned off the 20th led flashes. Removind F2 the display start to move from 10th to 20th led with full bright. 2- D1 and D6 heat up alot, i am doing a test with a 9v battery. IC3/IC4 output is only 3.4v (?), input is 5.9v (battery has 9.2v charge) looks like a short some where, but disconecting D1 and D6 IC3/IC4 operates fine outputing 5v. 3- D8 should drop the voltage to 2v and D9 should drop 0,7v giving me aprox 1.3 ref to LM3914, but there is a 4.3v final output, no good :-X 4- At point ENT-2 (signal input) there is a 1.5v, there is nothing connected there, where the voltage is coming from? (IC1/IC2 ??) 5- The LED brightness is not working also, that part of the circuit is doing what is supposed to do, it variates according to the light in the ambient but the display do not react to it.... :-\ Did i miss something??? PS: There is a point in the board that is not connected (IC4 GND), i connected that with a wire outsid the board. PS2: Board was build using Silk Screen. Thank you. O2-project.pdf

Does any one know or have any idea how o make the "Bar Display with alarm flasher" work with this configuation?? Because the design is too big already, i did have an idea to add to this circuit, a few extra 4148 diodes and a 555 so when the especific led turn on it will trigger the 555 to flash something or to buzz someting. Thanks.

Using LDR will be like "plug and play" so you don't need to mess up with the car cables. But the circuit is not ready yet, something must be done with the second LM3914, after that i still have to make the circuit blink or buzz when it reaches a certain level.

Trying to do a nice thing here, adding this LDR so when we have day light the display will be brighter and dimmish at night. I think this wil do.

Here is the incomplete schematic, looking the web to see if i could use a 741 at the input and define the values.

Here is the schematic for the voltage regulator, now to the LM3914 part....

Hello Audioguru, sorry, not Wilson but Wellington ;) Long time no see Audioguru, how are you?! You don't have that schematic around, did you? I was thinking the same about the input protection for the 7805, true is, i was thinking in using a 7806 instead to compensate the output protection also with a 5.1 zener, just in case the 7806 fails or who knows, stop working. I wil do the suggestions, i will keep monitoring the foruns for your reply :)

Yes, i got it! I have a few LM3914 here ;) I'm working on the schematic right now, the worst part is the "heavy filtering" part because the signal is only 1v max, there is the alternator part that can blow the regulator off (some friends os mine did that).

Hello audioguru, when you say "need heavy filtering" what do you have in mind?

Hello Capitain! Or should i call you General ;D Thanks for the schematic, there is a lot os these on the net. I want to try building one from scratch but if everything goes wrong i might use yours as reference! Audioguru knows me better when i pull out the stunt with 2 LM386 in a circuit that i called Super Headbanger. I enjoy learning new stuff ;D

But a "flash trail" means that the output transistor will be operating as a linear amplifier and getting very hot. You could do it with PWM and it would remain cool. No, no, no, what meant to say was to make the same effects with 4017 and LED's ;)

I wonder if this same effect could be made with a 4017 with some electrolitics capacitors at the output to make that flash trail behind or some delay when the light change from one channel to another.

Hello Guys! I'm doing a O2 meter for my car because pay about $150 bucks for a simple meter will not do for me, too much. So, i want to build a meter with 2 LM3915 for better resolution but i have a few questions: 1 - the car voltage is too unstable, there is too much oscilation, mechanical relays turning on/off, sparks, so i will use a 7805 to regulate the 12v. But there is one more thing, how to protect the 7805 from over voltage at the input from the car electric system? 2- In the National LM3915 datasheet there is a way to make the display to flash if the "warning" led lit up (Bar Display with alarm flasher), how to make this work with 2 LM3915? 3- The signal from the lambda sensor came with some noise, so grounding the signal with a 1M ohm resistor with a 1n capacitor could filter that with out killing the signal? Suggestions?

Here you will find all the information you need: http://www.videohelp.com/

Here is the final board and schematic for the circuit, i also included the project i've made with Eagle, enjoy! Hafler.zip Hafler.pdf

Thanks Audioguru