Need some help.
If anyone has a Digital Generator sensor bypass that comes with the new Bradley Cold Smoke Adaptor I would like to buy it from you. Just pm me.
TY
nepas
Nepa, I may be wrong but the little thingie they give you is just a dummy plug. I assumed it was a shorted plug for some reason, but when I checked with an ohmeter it was open.
I think that it is just a Radio Shack item if you take your cord so they can match. If anyone else has checked this dummy plug, let us know as I have not used my cold smoke setup yet.
I would think there is more to it than just an open plug because the smoke generator will not run with out the sensor plugged in. I agree it is something very simple that creates the ability to bypass or simulate the sensor.
Mike
Quote from: Mr Walleye on January 28, 2009, 07:29:50 AM
I would think there is more to it than just an open plug because the smoke generator will not run with out the sensor plugged in. I agree it is something very simple that creates the ability to bypass or simulate the sensor.
Mike
You are correct Mike there is a small device in it to simulate the sensor ( I don't know the type or name of it )
But an open plug will not work.
Brian
I was going to fit my BPS to this unit. Would work fine in the summer where it could be outside, but dont think i want the flame in the garage in the winter.
nepas
Thanks Brian
I guess not knowing if the sensor is a thermocouple, an RTD, or a thermistor it's difficult to know. I would assume its a thermocouple. A thermocouple is simply made of 2 dissimilar metals with a connection point. Based on the information below the 2 dissimilar metals when heated produce an electrical current which is measured and displayed as a temperature.
So... what does this mean?
Well... to me it means it should be very easy to bypass this providing your not concerned with the temp that is displayed. The display is showing what current it's getting from the TC and showing it as a temperature. I would bet you could simply take a connector and short the ends our with two dissimilar conductors. Obviously if the circut in the DBS does not sense any current it does not allow anything to run.
Hmmm... almost sounds like an experiment! ::)
PS... I'm definitely no expert on this and I would consult someone with more expertise in it. I may do some playing with this idea and if I do I will let you know.
It would certainly be easier if someone who has purchased the Bradley Cold Smoke attachment for an OBS would mail NePas the the bypass sensor because they would have no use for it.
Just thinking out loud....
Mike
How does a thermocouple work?
T.J Seebeck discovered in the 1820s that an electric current flows in a closed circuit of two dissimilar metals when one of the two junctions is heated with respect to the other. In a thermocouple circuit the current continues to flow as long as the two junctions are at different temperatures. The magnitude and direction of the current depends on the temperature difference between the junctions and the properties of the metals used in the circuit. This is known as the Seebeck effect. Click here to see an example of the circuit.
If the circuit is broken at the center, the net open circuit voltage (the Seebeck voltage) is a function of the junction temperature and the composition of the two metals.
If the hot and cold junctions are reversed, current will flow in the opposite direction. Any two dissimilar metals can be used and the thermocouple circuit will generate a low voltage output that is almost (but not exactly) proportional to the temperature difference between the hot junction and the cold junction. The voltage output is between 15 and 40µV per degree C, dependant on the thermocouple conductor metals used. The actual metals used in industrial thermocouples depend on the application and temperature measurement range required.
Mike, if it were only that easy. It can't be a thermocouple because I tried exactly what you mentioned. I bought a connector and soldered the two leads together. When it is plugged in, the BDS shows an 'E' just like the sensor was not connected. Maybe there is a resistor or something like that in the bypass. If someone has one it would be very interesting to see what is inside, it should be very easy to make once the mystery item is discovered.
Pens
I think whatever it is it must have to produce a current because that's basically what a TC does. Or at least that's how I understand it. When you did that did you us two different types of wire?
Mike
No because I can short a thermocouple out and it will read ambient temp. We use tons of thermocouples at work and many many times I'll short the connections out to make sure the right wire goes to the correct instrument, when shorted you can see the reading on the instrument change. It doesn't matter if it is shorted at the instrument or at the thermocouple. If you want to try something, unhook the thermocouple on your PID and touch a wire across the two screws, it should read about ambient temp.
I guess I could bring home a piece of actual thermocouple wire, not thermocouple extention wire, and try connecting it. But my gut feeling is it will not work. I'll try to remember to bring a piece home tomorrow. Actual thermocouple wire is made of two dissimilar metals as you mentioned.
Quote from: Bradley (Head Office) PR on January 28, 2009, 07:44:25 AM
Quote from: Mr Walleye on January 28, 2009, 07:29:50 AM
I would think there is more to it than just an open plug because the smoke generator will not run with out the sensor plugged in. I agree it is something very simple that creates the ability to bypass or simulate the sensor.
Mike
You are correct Mike there is a small device in it to simulate the sensor ( I don't know the type or name of it )
But an open plug will not work.
Brian
Maybe i should clarify this better
The Temp sensor in the digital smoker is a Thermistor.
When i said i didn't know the type i meant the type that is installed in the bypass plug.
Sorry for the confusion
Brian
OK, thanks Brian.
I'll see what I can find out about thermistors at work tomorrow. I know we only we thermocouples but I can check in some of our referance material, it may tell me something.
Thanks Brian
So Pens... You are probably correct regarding the resistor. I found this regarding thermistors
Thermistors are temperature sensitive resistors. All resistors vary with temperature, but thermistors are constructed of semiconductor material with a resistivity that is especially sensitive to temperature.
Mike
now i'm at at a loss here :D
nepas
I just did some quick googling. Thermistors are a temperature sensitive resistor (like Mike found out), so that being said. If I were to measure the resistance of the thermistor at room temperature, I would think installing a resistor with about the same value would do the trick.
If I can get some time to play at work tomorrow, I'll try to see if it works.
OK Sparky, enough drinking at a distance..... you can jump in anytime and help us out. ;D
NePas
Hopefully someone who has purchased the Bradley Cold Smoke attachment for an OBS and doesn't need the sensor bypass designed for the DBS will pass it along to you. At least that would be the simplest...
If not we'll get something figured out...
Mike
Quote from: pensrock on January 28, 2009, 05:33:35 PM
I just did some quick googling. Thermistors are a temperature sensitive resistor (like Mike found out), so that being said. If I were to measure the resistance of the thermistor at room temperature, I would think installing a resistor with about the same value would do the trick.
If I can get some time to play at work tomorrow, I'll try to see if it works.
OK Sparky, enough drinking at a distance..... you can jump in anytime and help us out. ;D
I think your onto it Pens! ;)
Mike
If someone could tell me what other test to do on this little "dummy plug" I will try.
If you have a multimeter (resistance to be exact), measure the resitance from the center conductor to the outer conductor. Should be a very low resistance. I suspect the actual circuit is only a very small resistor, maybe a couple ohms at the most.
I thought I have a few resistors around here to test this with but I guess the last clean up did a toss of unused parts.
OK guys here's what to do. Its real easy! ;D
I took one of my cables from the Bradley, that runs from the generator to the tower sensor, cut it in half. Then soldered a resistor to the wires. It works great. You can also buy a plug and solder the resistor to it, that way you still have your original Bradley cable if you want to use it. The 100K resistor simulates a temperature of 77 degrees F, it may vary slightly but should read about the same all the time.
Parts needed:
2.1mmx5.5mmx9.5mm DC Plug
100K-Ohm resistor 1/4 watt is plenty.
1/8 watt would work also.
(I got a pack of five at Radio Shack for a dollar, all they had was 1/4 watt) Radio Shack part #271-1347.
Unfortunately Radio Shack does not sell just the plug. They do have a plug with a wire and connector on it but its too much money. It was listed in another forum message some time ago.
You can buy a plug at Parts Express online for $1.25 part #090-477. http://www.parts-express.com/
They also have resistors, .55 for a pack of ten. Part #002-100K These are 1/2 watt they do not list 1/4 or 1/8 watt. !/2 Watt will work just fine, it's just a little larger.
I would bet they have the 1/4 watt if you were to call an order in, if you call them tell them you want the items shipped by mail to save on shipping. Last time I ordered from them they had no problem doing this for me.
Pens! Great Job! 8)
Two thumbs up! ;)
Mike
Ok pens
Your hired to do mine ;D
nepas
Thats pretty good to know because I looked for my dummy plug to mail to anyone who would check it, and now I can't find the little thingie!
NEPAS,
Let me know how many you need.
I've got him hooked up as soon as the rest of his parts arrive (as well as the rest of my order).
Pens
Just for the sake of doing it I made a couple this morning. I used the 1/8 watt 100k ohm resistors and it worked perfect. They are small enough to fit right in the connector under the cap. It reads 77 degrees. The only down side... Holly crap are they small to try and read! I had a package of 100 various 1/8 watt resistors! A magnifying glass is a must!
Anyway I thought I would throw the color code out there if anybody needs it.
100K-Ohm resistor, 1/8 watt, 5% carbon = Brown - Black - Yellow - Gold
Mike
QuoteHolly crap are they small to try and read!
I know what you mean. ;D ;D
Mine read 77 degrees also. When I checked the thermistor it was a little cooler in the shop, I got a reading of 118K. I had to use 1/4 watt because that was all I could find. I thought 1/8 would fit under the cap but was not sure.