Diode/LED Tester Circuit Design
Budget: $250 – $750 USD
Diode/LED Tester. I will supply BOM and Layout. This is my first circuit card.
- Derating: move to components that are derated (e.g., resistors at ≥60% rated dissipation when practical; capacitors with voltage margin).
- Capacitors: prefer electrolytic/solid polymer or MLCC X7R for stability; avoid low-stability dielectrics where long-term drift matters. Increase voltage rating (e.g., use 2× expected voltage where space/cost allow).
- Resistors: use metal-film or MELF where low tempco is important; increase power rating or spread dissipation (split resistor network) for hot spots.
- Semiconductors: choose devices with higher Vce/Vrrm margins, higher junction-to-ambient thermal resistance margins, and robust SOA for likely transient currents. Prefer packaged parts with better thermal pads (e.g., DPAK vs. SOT-23 if current allows).
- Inductors/transformers: prefer parts with better thermal class and lower core loss; specify rated current with margin and provide alternate vendors. Consider slightly larger cores or gapped cores if saturation is a concern.
- Thermal management: recommend copper pours, thermal vias under hot parts (if PCB layout can be changed), and keep-out / spacing rules.
- Simulations: run parametric sweeps across input (7–9 V), temperature extremes (4–49 °C), and component tolerances to show robustness.
Q.; Which exact PSpice version are you using today, and do you want full compatibility with a specific student edition release?
A. Software Version: Student 9.1
Q. Can you send the current PSpice project, PCB layout files and the original BOM in their native formats?
A. I do not have any current PSpice project, PCB layout files, and the BOM is mine.
Q. What input voltage range, load range and ambient temperature range should the circuit be guaranteed to survive and operate in?
A. The input is a standard 9DCV battery. The load range should be 7v - 9v. The ambient temperature range is 40F-120F
Q. Have you seen any real failures or “hot spots” on the existing board (burned parts, discolored PCB, very hot components) that you want me to focus on first?
A. This is my first prototype.
Q. Do you have an approved parts list or preferred manufacturers, or should I simply avoid locking parts to a single vendor and give at least two good options where possible?
A. I do not have list of approved manufacturers. I am looking for the cheapest and giving the customer the best for the value.
Q. Which PCB design tool was used for the current board so I can update the layout correctly and export Gerbers in the format your manufacturer expects?
A. This is the initial PCB design tool. I will make my own circuit board.
Q. Are there any mechanical limits I must not change, such as board outline, mounting holes, connector positions or keep-out zones?
A. I sent you a diagram of the mount holes and the wiring for the circuit board.
Q. Do you already have any thermal measurements or IR camera images of the current board, or should I rely only on simulation and calculated power dissipation?
A. None Just us the simulation and calculate the power dissipation.
- Derating: move to components that are derated (e.g., resistors at ≥60% rated dissipation when practical; capacitors with voltage margin).
- Capacitors: prefer electrolytic/solid polymer or MLCC X7R for stability; avoid low-stability dielectrics where long-term drift matters. Increase voltage rating (e.g., use 2× expected voltage where space/cost allow).
- Resistors: use metal-film or MELF where low tempco is important; increase power rating or spread dissipation (split resistor network) for hot spots.
- Semiconductors: choose devices with higher Vce/Vrrm margins, higher junction-to-ambient thermal resistance margins, and robust SOA for likely transient currents. Prefer packaged parts with better thermal pads (e.g., DPAK vs. SOT-23 if current allows).
- Inductors/transformers: prefer parts with better thermal class and lower core loss; specify rated current with margin and provide alternate vendors. Consider slightly larger cores or gapped cores if saturation is a concern.
- Thermal management: recommend copper pours, thermal vias under hot parts (if PCB layout can be changed), and keep-out / spacing rules.
- Simulations: run parametric sweeps across input (7–9 V), temperature extremes (4–49 °C), and component tolerances to show robustness.
Q.; Which exact PSpice version are you using today, and do you want full compatibility with a specific student edition release?
A. Software Version: Student 9.1
Q. Can you send the current PSpice project, PCB layout files and the original BOM in their native formats?
A. I do not have any current PSpice project, PCB layout files, and the BOM is mine.
Q. What input voltage range, load range and ambient temperature range should the circuit be guaranteed to survive and operate in?
A. The input is a standard 9DCV battery. The load range should be 7v - 9v. The ambient temperature range is 40F-120F
Q. Have you seen any real failures or “hot spots” on the existing board (burned parts, discolored PCB, very hot components) that you want me to focus on first?
A. This is my first prototype.
Q. Do you have an approved parts list or preferred manufacturers, or should I simply avoid locking parts to a single vendor and give at least two good options where possible?
A. I do not have list of approved manufacturers. I am looking for the cheapest and giving the customer the best for the value.
Q. Which PCB design tool was used for the current board so I can update the layout correctly and export Gerbers in the format your manufacturer expects?
A. This is the initial PCB design tool. I will make my own circuit board.
Q. Are there any mechanical limits I must not change, such as board outline, mounting holes, connector positions or keep-out zones?
A. I sent you a diagram of the mount holes and the wiring for the circuit board.
Q. Do you already have any thermal measurements or IR camera images of the current board, or should I rely only on simulation and calculated power dissipation?
A. None Just us the simulation and calculate the power dissipation.
Related categories:
Electronics
Electrical Engineering
PCB Layout
Circuit Design
Thermal Analysis
Simulation