The other day I was working the basement, and as I was working, to my horror, I heard a faint beeping noise. You see, I have created a homemade incubator as an electronics project. While creating the incubator, I decided to add an alarm feature if the temperature raises above 102 degrees F. It checks once roughly every two seconds. The electronics project has been quite a learning curve about how relays and light bulbs work.
It turns out that CFL light bulbs are quite difficult to work with to adjust temperature with using a relay. While the light bulb itself may only draw 23 watts while running, the start up wattage is more like 230 watts, or even 345 watts. Doing a little math, this is roughly 0.2 amps(23 watts), 1.92 amps(230 watts) and 2.87 amps(345 watts).(CFL start up wattage is about 10 - 15 times the operating wattage, however this can be worse if you are cycling the light bulb on and off quickly, as the light bulbs aren't designed to operate in such a fashion. Often times the light bulb uses a heat sensitive element to make it have a slower powerup wattage) This was very problematic for me because I had only purchased a 2 amp relay, and 2.87 amps way above my little relay's ability. The symptom is that the relay would turn on, but then would be stuck on. I was able to dig up a 60 watts(0.5 amp) incandescent light bulb, and magically my relay started working! See, the incandescent bulb doesn't have the same start up problem as CFL light bulbs.
Well, that isn't the end of the story. During my research I discovered the following graph.
Well, what does it mean? I'm going to assume that each on/off cycle is an operation(I could be wrong here.) Well, I found with my 60 watt light bulb in my little incubator means that I cycle the light bulb about 3 times a minute. Looking at the graph, I'm using about 0.5 amps of power using a resistive load, so I should get about 70,000 cycles. Doing a little math, that gives me about 16.2 days. Well, I have already hatched a group of eggs, so I knew I was already pushing my luck when I started my next batch of eggs. With the electrical service life, I figured that the contacts would just stop responding, or prevent the light bulb from turning on. I was okay with that. I had also ordered a new 10 amp relay for a new incubator with the following graph, which using a 0.5 amp resisitve load, should give me about 1,000,000 operations before failure, or 231.48 days of operation with the light bulb cycling 3 times a minute.
Enough of theory, back to the story. In my horror, I hear that tiny beeping noise. I drop my work and run to the adjacent room. I open my incubator, and to my horror, the temperature in the incubator reads 138 degrees F. I fear for the worst, that I've just killed all of my little eggs. I kept thinking to myself, I should've known better. I shouldn't of pushed my luck with something I knew was going to fail! Frantically I start tapping the relay, thinking maybe it is just stuck. The light bulb just stayed on. In horror, I knew that I had pushed my relay to it's limits. I quickly unplugged the incubator and slowly walked upstairs to tell my wife that I had just cooked our latest batch of eggs. To make things worse, we lost one of the mamma birds that had graciously donated her eggs.
After sitting there for several minutes, trying to get my thoughts in order, it occurred to me, what if that was the first alarm I received. Perhaps, the eggs hadn't been cooked yet. Perhaps they are alive? We turn on our store bought incubator, and put the eggs in there. My homemade incubator also logs the temperature every 15 minutes. I pulled out my computer and brought up the temperature log. The good news was that the only the latest store temperature was high. How high... Let's just say a lot higher than 138 degrees F. The thermometer I'm using for the project is more sensitive than the thermometer that is independent of the incubator. While it was good news to find that only one 15 minute interval contained a temperature spike, the question loomed in my mind, which part of the 15 minute interval? Was it the whole 15 minutes, or just a couple of seconds? We broke open and measured the internal temperature of one of the eggs. It read 100.8 degrees F, so there is hope!
The next day I was able to find some time to replace the relay in my incubator, which required a few extra components because I needed more current to power the new relay. With the relay replaced, we put half of the eggs in my "fixed" incubator, and left the other half in the store bough incubator. We didn't want to leave all the eggs in one incubator, but the store bought one doesn't have a very good hatch rate.
Now yesterday marks on 7 day mark on this batch of eggs. We candled last night, and it looks like the eggs are alive and well, but I've never been very good at candling.
I'll try and keep everyone updated on what happens with this batch of eggs.
It turns out that CFL light bulbs are quite difficult to work with to adjust temperature with using a relay. While the light bulb itself may only draw 23 watts while running, the start up wattage is more like 230 watts, or even 345 watts. Doing a little math, this is roughly 0.2 amps(23 watts), 1.92 amps(230 watts) and 2.87 amps(345 watts).(CFL start up wattage is about 10 - 15 times the operating wattage, however this can be worse if you are cycling the light bulb on and off quickly, as the light bulbs aren't designed to operate in such a fashion. Often times the light bulb uses a heat sensitive element to make it have a slower powerup wattage) This was very problematic for me because I had only purchased a 2 amp relay, and 2.87 amps way above my little relay's ability. The symptom is that the relay would turn on, but then would be stuck on. I was able to dig up a 60 watts(0.5 amp) incandescent light bulb, and magically my relay started working! See, the incandescent bulb doesn't have the same start up problem as CFL light bulbs.
Well, that isn't the end of the story. During my research I discovered the following graph.
Well, what does it mean? I'm going to assume that each on/off cycle is an operation(I could be wrong here.) Well, I found with my 60 watt light bulb in my little incubator means that I cycle the light bulb about 3 times a minute. Looking at the graph, I'm using about 0.5 amps of power using a resistive load, so I should get about 70,000 cycles. Doing a little math, that gives me about 16.2 days. Well, I have already hatched a group of eggs, so I knew I was already pushing my luck when I started my next batch of eggs. With the electrical service life, I figured that the contacts would just stop responding, or prevent the light bulb from turning on. I was okay with that. I had also ordered a new 10 amp relay for a new incubator with the following graph, which using a 0.5 amp resisitve load, should give me about 1,000,000 operations before failure, or 231.48 days of operation with the light bulb cycling 3 times a minute.
Enough of theory, back to the story. In my horror, I hear that tiny beeping noise. I drop my work and run to the adjacent room. I open my incubator, and to my horror, the temperature in the incubator reads 138 degrees F. I fear for the worst, that I've just killed all of my little eggs. I kept thinking to myself, I should've known better. I shouldn't of pushed my luck with something I knew was going to fail! Frantically I start tapping the relay, thinking maybe it is just stuck. The light bulb just stayed on. In horror, I knew that I had pushed my relay to it's limits. I quickly unplugged the incubator and slowly walked upstairs to tell my wife that I had just cooked our latest batch of eggs. To make things worse, we lost one of the mamma birds that had graciously donated her eggs.
After sitting there for several minutes, trying to get my thoughts in order, it occurred to me, what if that was the first alarm I received. Perhaps, the eggs hadn't been cooked yet. Perhaps they are alive? We turn on our store bought incubator, and put the eggs in there. My homemade incubator also logs the temperature every 15 minutes. I pulled out my computer and brought up the temperature log. The good news was that the only the latest store temperature was high. How high... Let's just say a lot higher than 138 degrees F. The thermometer I'm using for the project is more sensitive than the thermometer that is independent of the incubator. While it was good news to find that only one 15 minute interval contained a temperature spike, the question loomed in my mind, which part of the 15 minute interval? Was it the whole 15 minutes, or just a couple of seconds? We broke open and measured the internal temperature of one of the eggs. It read 100.8 degrees F, so there is hope!
The next day I was able to find some time to replace the relay in my incubator, which required a few extra components because I needed more current to power the new relay. With the relay replaced, we put half of the eggs in my "fixed" incubator, and left the other half in the store bough incubator. We didn't want to leave all the eggs in one incubator, but the store bought one doesn't have a very good hatch rate.
Now yesterday marks on 7 day mark on this batch of eggs. We candled last night, and it looks like the eggs are alive and well, but I've never been very good at candling.
I'll try and keep everyone updated on what happens with this batch of eggs.
