Willen
Well-Known Member
I have many many such devices (attached circuit) but all are damaged. There's a delicate chip (it should be) inside but it's being operated with horrible supply- just a diode and a resistor. I think the main reason of the damage is surge voltage during ON or OFF or sparking on switch or on plug.
I am thinking to fix it with pretty nice regulated and reliable circuit. I think if the IC gets totally safe supply, it would survive till many decades! IC prefix are different like- B-803A, YL 803, XX803, Q803 etc but all are same. Datasheet is not available (I didn't find easily).
Main questions are:
- First thing I decided to add a zener diode of 4.7V across C1 capacitor. I measured 3.7V across the C1 (22uF) while the device was operating. And decided to add another 3.3V zener from 10th pin to 9th pin. (Voltage across 10th pin to 9th pin was 2V while operating.) It is just to block high surge voltage from resistor.
-Second, I am thinking to use a safe SMPS (like 220V AC to 3.7V DC or etc) to supply the IC. But one thing is confusing me- Look at the 2Meg resistor. The supply for 10th pin has taken directly from AC line, but why? (10th pin has +2V, referenced to 9th pin). Maybe the IC takes 'clock frequency' of 50Hz from the mains. If so then I cannot feed just 2V there in the 10th pin from SMPS. What you think?
Regards
I am thinking to fix it with pretty nice regulated and reliable circuit. I think if the IC gets totally safe supply, it would survive till many decades! IC prefix are different like- B-803A, YL 803, XX803, Q803 etc but all are same. Datasheet is not available (I didn't find easily).
Main questions are:
- First thing I decided to add a zener diode of 4.7V across C1 capacitor. I measured 3.7V across the C1 (22uF) while the device was operating. And decided to add another 3.3V zener from 10th pin to 9th pin. (Voltage across 10th pin to 9th pin was 2V while operating.) It is just to block high surge voltage from resistor.
-Second, I am thinking to use a safe SMPS (like 220V AC to 3.7V DC or etc) to supply the IC. But one thing is confusing me- Look at the 2Meg resistor. The supply for 10th pin has taken directly from AC line, but why? (10th pin has +2V, referenced to 9th pin). Maybe the IC takes 'clock frequency' of 50Hz from the mains. If so then I cannot feed just 2V there in the 10th pin from SMPS. What you think?
Regards
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