Low Pellet Detection Buzzer Constantly On

[Peoples-Exchange]

Hey guys so I have finally gotten my build to the point where I can begin testing and fine tuning but have an annoying problem. I did not order the Low Pellet Detection so i have 4 bare pins on my PCB. Every time I turn the spooler motor switch on I get a constant alarm from the buzzer. Is the PCB wired to sound the buzzer when the Low pellet emitter gets 0V? This was the only thing I could think of that would cause me to hear the alarm constantly (unless the buzzer is shorting out somewhere I don't see)  since no voltage is being received by the low pellet pins on the pcb. Does anyone have any suggestions on how to get the alarm to turn off without purchasing the low pellet detection add on? Any help would be much appreciated!

[Herb Winters]

Hi that is not normal I double checked here by connecting a board to 24vdc with nothing else connected.
if I short the D-PT (Detector for pellets) to the pin below it marked 5V then the alarm will sound. but if nothing is connected to that pin then you should not be hearing the alarm.
does everything else on the board work like the spool motor start and stop?

[Peoples-Exchange]

Thanks Herb,

I assumed the alarm was not on by default but figured I would ask before I started poking around. Turns out my buzzer was shorting on the board itself. I just pushed it over a bit and the buzzing stopped. HOWEVER now my spooler motor turns constantly and shows no reaction to my finger being placed between emitter and detector. Everything is wired correctly (to my knowledge) according to your schematic (Thank you by the way!). I am using the IR emitter and detector from Radio Shack and not the ones that were supposed to ship with the kit. If I test the pins with my dmm i see ~1.25v on the emitters and ~.625 on the detectors. Using a cell phone camera I can not see any "blue" light coming from either of the emitters. I have tried switching both polarity and the position of the top / bottom emitters with no change. Any suggestions on where to start trouble shooting? I am also a little hazy on what normal operation should be. If top detector is receiving an IR signal the motor should be off?, and if bottom IR detector signal is broken spooling should begin? Again your help is greatly appreciated. 

[Peoples-Exchange]

Ok so I am a little closer but still not fully operational. Turns out that the Radio shack emitter and detector are opposite my assumption. The black led is the emitter and the clear led is the detector...oops. Once I figured that out I was able to swap emitters and detectors but still the motor continued to turn without any reaction from breaking the IR beam top or bottom. I then disconnected both emitters and hooked them up to CR2023 3V batteries. This produced a visible red light from the emitter and after turning on the motor spool switch the motor began to respond when the bottom beam was blocked by my finger. Success! I can now confirm both detectors are operational. The PCB is supplying 1.2v and the emitters according to the radio shack specs should run at 1.5-1.8v. Im somewhat surprised the 1.25v isn't working but the temporary 3v battery is. Were the original LED's supplied 1.2v? I guess I could just purchase new emitters. Thoughts? Any one else running into problems with the radio shack LED's? 

[Herb Winters]

Hi Sorry I have been running around a lot and have not had much time.
if the Radio-shack Emitters have a higher VF than the original it is possible that they are turning on but not being given enough current to turn on the Detector I have been working on fully understanding the Board electronics as I do not have a schematic it takes a little more time. But by the weekend I will try to get you the resistors numbers that you need to change and the new values you will need and if I can I will give you a part number to order. in the mean time be careful running the emitter off of a 3V coin cell. you can damage the Emitter unless you have a resistor in series with the battery. it may not happen but is possible, depends on the Max current rating of the Emitter and type and manufacture of the coin cell.

[Herb Winters]

Here is a Descrition of how all functions work from the 5 units I have worked on.

on Board power up

Pellet Detection:
if the D-PT detects IR light then the alarm will sound (D-PT is pulled to 5V by detecter)
once D-PT now longer detects IR light the alarm will turn off ( D-PT is open)

Fan:
On Power up supplies 12VDC to fan out. does not shut off

Spool Motor:
Both IR Emitters E-TOP and E-BOT are turned on at power-up and do not turn off

on power up if both D-TOP and D-BOT detect IR then the state is unknown some units will turn on others turn off.
after this the state of the spool motor is a latching function
When the D-TOP Detects a lack of IR light it will set the motor state to OFF
When the D-BOT detects a lack of IR light it will set the motor state to ON

if both D-TOP and D-BOT detect a lack of IR light at the same time the motor state will be on until only one detects a lack of IR light then it will set the state as above.

this is observed behavior I hope to have the circuit understood by the weekend.
I will let everyone know what I find.

[Peoples-Exchange]

Thanks so much Herb! Your write up of basic operation is very helpful. I ended up ordering new IR LED's that operate at 1.2v and are still 850nm in wavelength. If anyone else is looking for emitters here is the amazon link: http://www.amazon.com/gp/product/B0066AYPX6/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1 . The kit comes with 200 resistors and 100 5mm IR LED's for ~$13. Seems a better deal to me than spending the $3.99 for a single emitter detector pair from radio shack. I will update when I receive them on Saturday. I am anxious to get the spooler functioning properly seeing as all other functions seem to be operating correctly. 

[Herb Winters]

Thanks, I'm Glad to help!

I have finished looking over the PCB and there are lots of problems but, for now I will stick with Basic Information.
 
for those of you trying to verify that you have the correct components installed.

The correct Values for the components are as follows:

R1 = 10K Ohms, 5% (digit 1 Band = Brown, digit 2 Band = black, Number of zeros Band = Orange, Tolerance Band = Gold)
R2 = 4.7K Ohms, 5% (digit 1 Band = Yellow, digit 2 Band = Violet, Number of zeros Band = Red, Tolerance Band = Gold)
R3 = 1K Ohms, 5% (digit 1 Band = Brown, digit 2 Band = black, Number of zeros Band = Red, Tolerance Band = Gold)
R4 = 4.7K Ohms, 5% (digit 1 Band = Yellow, digit 2 Band = Violet, Number of zeros Band = Red, Tolerance Band = Gold)
R5 = 1K  Ohms, 5% (digit 1 Band = Brown, digit 2 Band = black, Number of zeros Band = Red, Tolerance Band = Gold)
R6 = 10K Ohms, 5% (digit 1 Band = Brown, digit 2 Band = black, Number of zeros Band = Orange, Tolerance Band = Gold)
R7 = 1K  Ohms, 5% (digit 1 Band = Brown, digit 2 Band = black, Number of zeros Band = Red, Tolerance Band = Gold)
R8 = 330 Ohms, 5% (digit 1 Band = Orange, digit 2 Band = Orange, Number of zeros Band = Brown, Tolerance Band = Gold)
R9 = 330 Ohms, 5% (digit 1 Band = Orange, digit 2 Band = Orange, Number of zeros Band = Brown, Tolerance Band = Gold)
R10 = 1K Ohms, 5% (digit 1 Band = Brown, digit 2 Band = black, Number of zeros Band = Red, Tolerance Band = Gold)
R11 = 4.7K Ohms, 5% (digit 1 Band = Yellow, digit 2 Band = Violet, Number of zeros Band = Red, Tolerance Band = Gold)
R12 = 330 Ohms, 5% (digit 1 Band = Orange, digit 2 Band = Orange, Number of zeros Band = Brown, Tolerance Band = Gold)
R13 = 1K Ohms, 5% (digit 1 Band = Brown, digit 2 Band = black, Number of zeros Band = Red, Tolerance Band = Gold)
R14 = 1K Ohms, 5% (digit 1 Band = Brown, digit 2 Band = black, Number of zeros Band = Red, Tolerance Band = Gold)

U1 = 7812 Voltage Regulator
U2 = Two Resistors 100 Ohms each inserted to make a voltage divider, 5% (digit 1 Band = Brown, digit 2 Band = black, Number of zeros Band = Brown, Tolerance Band = Gold)

Q1 = 2n3904 NPN general purpose transistor
Q2 = 2n3904 NPN general purpose transistor
Q3 = 2n3904 NPN general purpose transistor
Q4 = 2n3904 NPN general purpose transistor

Top 14 pin DIP IC = SN74HC132N Quad Positive-NAND Gates With Schmitt-Trigger Inputs
Bottom IC = Meder Electronics DIP05- 1A57-BV350, Reed relay with +5Volt coil spst
Buzzer = no markings are visible other than HYDZ other than that I don;t know.

The board I used is marked "EB SCS ver 2.0"


 

[Peoples-Exchange]

I am disappointed to report that the emitters I purchased on amazon are not working with the detectors from radio shack. Not sure why considering they are the same wavelength. I also checked my pcb against Herb's write up and everything seems to be correct. I did notice that on R10, R13, and R14 you listed them as 1k Ohm resistors which is what I have on my board but you listed the Zeros Band as Orange and I believe it should say red. Unless they are supposed to be 10k resistors and my board has the wrong ones installed. Seeing as my spooler is still not functioning as expected I would appreciate a confirmation that they are in fact 1k and not supposed to be 10k. For the moment I am at a loss and will be contacting mark to try and get the appropriate emitter detector pair. Has anyone else used the radio shack pair with success? Could someone with the emitter detector pair from Mark take two voltage readings from the detector? One with emitter on and another reading with the emitter blocked? Please? My frustration levels are growing.....

[Herb Winters]

@Peoples-Exchange you are Right I messed up the band colors on the resistors (copy and paste errors) I have gone back and edited the previous comment so It should be correct now. Thanks for the feedback. Sorry it didn't help.

I have ordered two different LED emitters that I will test as soon as they come in and if they work then I will let you know the parts numbers and were to buy.

if you can get another set that would be the  quickest option at this point.

[Peoples-Exchange]

I finally got Mark to send me a new set of IR LED's and the spooler now functions. If D-Bot doesn't detect IR the spool motor turns on. However it still does not spool consistently and I am at a loss for how to improve it. I am now considering designing my own spooling system from scratch with an Arduino but hoping it does not come to that. How are you making out? 

[Tim Elmore]

You should check out the Filawinder:

http://www.filastruder.com/collections/spare-parts/products/filawinder

+/-0.02mm when used with a Filastruder, though it will work with any extruder. The key to winding is constant tension on the filament. The Filawinder accomplishes this by using gravity and keeping the height of the loop constant.

[Peoples-Exchange]

Thanks! That does look like a good option and all things considered its reasonably priced. Is anyone on the forum using the filawinder with an extrusionbot?