I can recall opening one of these PulseStarter units when I was younger, but didn't have the skills to fully understand the operation. It's a lot clearer now, but there is still an oddity of how the thyristor that shunts the starter contacts is kept off if the tube doesn't strike. My guess is that it turns on just long enough to keep the transistor's base capacitor topped up, but not long enough to attempt a tube heat and strike.
It's actually quite a neat circuit. I wonder what sort of thyristor they used before this application specific thyristor was introduced. It would have to have a low gate current like a TIC106M.
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It's actually quite a neat circuit. I wonder what sort of thyristor they used before this application specific thyristor was introduced. It would have to have a low gate current like a TIC106M.
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When the tube is operated in cold cathode mode on an electronic ballast and the emissive coating wears out, it is still able to strike (because it is a high voltage of about 600V`), but it will get hotter and hotter until the lampholder melts or the tube acutally loses vacuum.
I have been using the same florescent tube and the same quick starter for 20 years.
Bob Almond ( comment below ) has just done my ( party fun ) idea from long ago ! …DAVE™ ………
Typical polystyrene capacitor. That little transistor is supposed to be a SCR. Ron W4BIN
Hey I'm in college right now finishing my developmental classes. When I'm done I wanted to get Into repairing electronics and stuff. What would that profession be named? Also how could I start learning now?
What language is this?
The thyristor doesn't kick in again because the fluorescent lamp has been started and its voltage between filaments has dropped below 170 volts of Zener diode, so thyristors gate has no chance of switching the thyristor again, unless voltage again goes up to 170 volts.
It is unbelievable that an ingeniously simple, reliable, cheap ecological and proven thing it occurs someone to replace with complicated, expensive, unreliable nonsense. Only two things in the universe are infinite. Economic growth and human stupidity.
Clive any possibility of showing the circuitry of flourescent emergency lights which incorporates an inverter and batteries along with the ballast. 🍻 cheers.
Why do you need the Starter though? What did I miss?
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Hello BC I have a neurostimulator which came out of my back. I would like to send it to you so you can examine it. It's a terrible expensive part so it could be very interesting.
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I think it is pure luck that the TN22 stays on when it is supposed to, as the resistor across the diode in series with the cathode is 24k. It is that resistor pulling down on the cathode that drains current from C1 back into the gate to retrigger it on the next 1/2 cycle. C1 is then topped up by the voltage fed out the gate due to the equivalent circuit of an SCR (an NPN & a PNP driving each other). The max. firing current of the TN22 is 1.5mA, and the current through the 24k, with a full volt across it is only 41.7uA. It is relying on the TN22 taking less current than the maximum spec. I would have expected something like 470R, or 560R max.
The SCR is a type called a gate turn off, or GTO. That high hold current rating is only with the gate grounded. Driving it negative will drive it off. Because the timing capacitor stays topped up, the darlington would quickly drive the gate down to about the same potential as the cathode, so it could be retriggering, but turning off again quickly. You could check that with a cro. The reason for making it a GTO would be to make it turn off while there is still at least 175mA flowing through it to produce the inductive spike to start difficult tubes. I think the 56k in series with the timing capacitor might be to produce a bit of ripple to turn on the darlington, or fire the cutoff SCR while there is current flowing through the TN22 to produce the spike. In mine it was a 6.8K. I don't know what it was for, as the original thyristor was a C106D, not a GTO. Just recheck the orange capacitor value to make sure it is not 10uF like mine. Let me know whether it is or not, and the number on the zener please, as well as the thermal fuse number, as mine is a standard metal one rated at 2A 125 deg C.
The capacitor in a glow switch starter is to weld the contacts together briefly. I tried one without and the contacts just buzzed and it 1/2 lit.
bigclivedotcom, the 82k resistor has to go to the SCR gate to get enough voltage to turn on the darlington, as it requires 2 diode drops. I traced the circuit out from another youtube video by an American guy, but in his one, the 82k was 100k and the 15k was 33k like the one I put in my rangehood. Yours must be designed for a fitting with 2 tubes in series or 120V. What is the number of the zener in yours? Is it is probably a BZX85C110. It looks like you wrote 170V. That's not a preferred value. I'm not sure if mine is a Pulsestarter brand. I would have to partly disassemble the hood to see. It looks the same, but a different layout and has the same circuit as the datasheet, and has a specially selected sensitivity P0124 SCR instead of a darlington. R1 is 33k, R2 & R4 are 6.8k, R3 is 24k, C1 is 10uF, C2 is 100uF and the main SCR is a C106D. I posted the circuit on stackexchange How to light a fluorescent lamp, along with a modified version I designed to suit available components, which has a relatively fixed on time instead of that circuit which mimics the response time of the filaments with variations in current.
i use those ballasts as load limiters as i have 3 400w ballasts that came from 2 high bay hid lights and one from a hps grow light . and kept the bulbs for a display piece . and soon will be gaining at least 10 more 70w twin fluorescent batten ballasts from an office that's getting torn down then rebuilt into a house . then i can build a variable load limiter when i burn things out using a bunch of light switches and a double gang socket