Hi, everyone! Can you help me finish designing a LED circuit which is protected by a thermistor? Schematic attached.
LED Light
1. 120VAC supply
2. protected/fused at 3A
3. Rectified into DC
4. Capacitor smoothes
5. Resistor slow-bleeds capacitor to prevent shock at plug (right ohms?)
6. 14 LED’s are the load, and used to drop all the supply voltage: prefer to keep at <120 Celsius
7. PTC thermistor nested in LED’s to aid in current control, especially runaway current due to heat.
Questions:
1. Is this circuit a good idea?
2. Is my R1 resistor placement and specifications a good idea?
3. Can someone help me choose a thermistor for this setup?
4. It seems that the circuit would ideally have around 126ohms resistance to limit current to the LED’s.
a. Is it possible to use the thermistor for this resistance?
BOM
ITEM DESCRIPTION SPECIFICATIONS PN
C1 Capacitor Aluminum, 400V, 560uf 380LX561M400A052
B1 Rectifier Bridge, 800V, 4A GBU4K-BPMS-ND
R1 Resistor 1Mohm, 1watt FMP100JR-52-1M
D1 Blue LED 9-11V, 900-1050ma ebay
F1 Fuse Fast blow. 3a, 125V
T1 PTC Thermistor specs??
LED Light
1. 120VAC supply
2. protected/fused at 3A
3. Rectified into DC
4. Capacitor smoothes
5. Resistor slow-bleeds capacitor to prevent shock at plug (right ohms?)
6. LED’s are the load: prefer to keep at <120 Celsius
7. PTC thermistor nested in LED’s to aid in current control, especially runaway current due to heat.
Questions:
1. Is this circuit a good idea?
2. Is my R1 resistor placement and specifications a good idea?
3. Can someone help me choose a thermistor for this setup?
4. It seems that the circuit would ideally have around 126ohms resistance to limit current to the LED’s.
a. Is it possible to use the thermistor for this resistance?
Schematic attached.
Thanks very much for any help!!
LED Light
1. 120VAC supply
2. protected/fused at 3A
3. Rectified into DC
4. Capacitor smoothes
5. Resistor slow-bleeds capacitor to prevent shock at plug (right ohms?)
6. 14 LED’s are the load, and used to drop all the supply voltage: prefer to keep at <120 Celsius
7. PTC thermistor nested in LED’s to aid in current control, especially runaway current due to heat.
Questions:
1. Is this circuit a good idea?
2. Is my R1 resistor placement and specifications a good idea?
3. Can someone help me choose a thermistor for this setup?
4. It seems that the circuit would ideally have around 126ohms resistance to limit current to the LED’s.
a. Is it possible to use the thermistor for this resistance?
BOM
ITEM DESCRIPTION SPECIFICATIONS PN
C1 Capacitor Aluminum, 400V, 560uf 380LX561M400A052
B1 Rectifier Bridge, 800V, 4A GBU4K-BPMS-ND
R1 Resistor 1Mohm, 1watt FMP100JR-52-1M
D1 Blue LED 9-11V, 900-1050ma ebay
F1 Fuse Fast blow. 3a, 125V
T1 PTC Thermistor specs??
LED Light
1. 120VAC supply
2. protected/fused at 3A
3. Rectified into DC
4. Capacitor smoothes
5. Resistor slow-bleeds capacitor to prevent shock at plug (right ohms?)
6. LED’s are the load: prefer to keep at <120 Celsius
7. PTC thermistor nested in LED’s to aid in current control, especially runaway current due to heat.
Questions:
1. Is this circuit a good idea?
2. Is my R1 resistor placement and specifications a good idea?
3. Can someone help me choose a thermistor for this setup?
4. It seems that the circuit would ideally have around 126ohms resistance to limit current to the LED’s.
a. Is it possible to use the thermistor for this resistance?
Schematic attached.
Thanks very much for any help!!
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