Induction brass annealer redux
- Thread starter Gina1
- Start date
Yeah I didn't even think about it. As I only have one switch I could try isolation. Thx! But for now I'd rather turn attention elsewhere. I'd like to have a dabble with a flame sensor following in the footsteps of @oliverpsmile et al.
(For others listening in I believe you mean simply having a diode in series with each wire going to the 'switch'.)
(For others listening in I believe you mean simply having a diode in series with each wire going to the 'switch'.)
I completely missed this as I was grappling with things. Could have saved me some time!
Gravity: Analog Flame Sensor For Arduino
The Arduino flame sensor detects fire or other wavelength at 760 nm ~ 1100 nm light. It outputs analog signal which is proportional with strength of fire or light. It is also compatible with Raspberry Pi.www.dfrobot.com
I see some are using the sensor modules with digital output, @oliverpsmile you linked to the analog one without pot. @itchyTF are you using the digital out? I'm wondering what would be the best direction to head...
I'm a bit confused by the first post above. I thought the trim pot was simply a triggered high/low output based on the analog signal from the sensor. So to adjust the threshold via there Arduino surely you take in the analog signal (rather than the digital output)... And if you're going to do the A/D conversion yourself then the simpler device Oliver linked to is more than suffice.
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I got a flame sensor with both a pot controlled logic output and the analog output. I think the analog output is the more flexible allowing monitoring the sensor close to 10K times per second if needed using a low end Atmega 328p. That's where gate control will come in handy if you want to control the (on/off cycle) duty cycle of the heater more quickly than either a relay or SSR could do.
Yes a diode that only allow the current to ground the gate, but will block the positive voltage from one side to charge the gate on the other side.
If you want to get fancy, one could control both gates directy with a single PWM pin at 50% duty cycle by varying the frequency to best match the case being annealed. But a lot of testing would need to be done to optimize the frequency. I think when the current through the heating coil near saturation (peaks off) then the polarity to the gates should be reversed. The frequency would change with the case type, placment and temp of the case.
Yes a diode that only allow the current to ground the gate, but will block the positive voltage from one side to charge the gate on the other side.
If you want to get fancy, one could control both gates directy with a single PWM pin at 50% duty cycle by varying the frequency to best match the case being annealed. But a lot of testing would need to be done to optimize the frequency. I think when the current through the heating coil near saturation (peaks off) then the polarity to the gates should be reversed. The frequency would change with the case type, placment and temp of the case.
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Correct! My flame sensor has only analog output.
The sensor is cut off from the board and is installed an inch from the case. Each caliber case lands on the same spot.
It's a pity they don't stock the simple YG1006 part. Sunrom sells them but not for delivery outside of India (at this time). Oh well. I just ordered some from Mouser. Thx!
Yes. I will revisit once I'm further along with the sensor.
I suspect you might be in for a real pile of difficulty trying to do this. The point of the board is it's self-oscillating (with a frequency dependent on the inductance of the work coil). I'd rather let it do its thing in this regard.
Sorry for the confusing post you referenced. I captured the raw analog output of the flame sensor and processed it through the A/D convertor on the Arduino. The Arduino A/D convertor then outputs a value of 0-1023 with 1023 being the value for the lowest temperature and 0 representing the hottest temperature. The POT on the sensor is not used in my implementation. I can adjust, on the fly, the value at which I stop annealing. This allows for very fine tuning of the amount of annealing the case receives and is constant no matter what the case size, thickness or brass characteristics.
I did a little test today that might come in handy calibrating the flame sensor. I have a simple braid/rope cutter. I also have a Brymen BM869s multimeter which is capable of measuring temperature from -58F to 1832F with 0.3% +3F accuracy. Conveniently the rope cutter blade 'settles' around 950/1000F.
I took a video. Not perfect but likely better than using Tempilaq. A varactor on the mains might lead to better control.
I took a video. Not perfect but likely better than using Tempilaq. A varactor on the mains might lead to better control.
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I do not do any smoothing of the readings from the flame sensor. I do record the final value of the sensor when annealing stops and it is usually within one of the set value, rarely is within two. (eg. my threshold to stop annealing is set at 50 and the final value is usually 50 or 49, rarely 48). As far as my eyes can tell, I get a very consistent glow from case to case, but I have not measured the actual temp of each case. I still feel I get a much more consistent anneal with the flame sensor than I was getting using either a set time or a set about of energy (Joules) to stop the anneal process, especially with mixed head stamp cases.
itchyTF
Gold $$ Contributor
A FWIW - for you guys that would like to put in a DC SSR (not made in china) ahead of the inductor board, I bought some Crydom D1D40's (100VDC, 40A). If all goes well I might have 6 or so left. The are listed as new and I'd be willing to sell what's left for $25 each plus shipping. Just wanted to know if there was any interest before I post this in the For Sale forum. Most of the guys in that forum probably wouldn't know what these are.
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Sent you a PM.
In the 1.88 sec of Arduino loop (maintaining 1000 F), every 0.01 sec the reading of IR sensor is averaged. Then, the Avg temperature value is compared with the 1000 F set up value. If the Avg value is below the set point the inductor is switched ON, other wise switched OFF.
The reading is erratic if the sampling is very fast . I've never measured how fast. This is why I average.
I also average every 100 readings when the case is heated to 1000 F,
Yes, it is the output from the 10 bit DAC. My experimenting demonstrated that distance to the object and ambient light both affect the "calibration". My initial temporary set up of the flame sensor had it a little further from the case and the calibration value needed was 32. With my permanent install of the sensor being closer the case, the value needed to be decreased to 50 (higher value = less glow). I did not want to anneal in the dark so my setting is for annealing in my normal ambient light. I noticed that the ambient light had less of an affect on the value than the sensor to object distance. I am careful not to anneal with sunlight from a window shining on the case.
itchyTF
Gold $$ Contributor
Got 4 Crydom D1D40 DC SSR’s for sale.
Thread 'Induction annealer - DIYers'
https://forum.accurateshooter.com/threads/induction-annealer-diyers.4063417/
Thread 'Induction annealer - DIYers'
https://forum.accurateshooter.com/threads/induction-annealer-diyers.4063417/
You can click "watch" without making the thread longer
As a practical matter, have you ever looked at how many times the induction board switches off/on during that 1.88s? Your duty cycle would have a maximum of a bit less than 100x a second (given computational time). I wonder how much in practice the temp of the brass moves more than +/- 2% (I think this is your toggle margin) during such a period.
Re your last point, just to be clear, you average on the way up to 1000F and during the 1.88s?
(As my entire control board code needs to fit into 12KB I need to be very careful about program memory usage.)
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