Garage Circuits

Welcome to Garage Circuits — a place where curiosity meets hands-on electronics. This blog is dedicated to DIY electronics, practical projects, and real-world circuit design that you can build yourself. Whether you're just starting out or already deep into the world of resistors, microcontrollers, and oscilloscopes, you'll find something useful here.

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Why does my key fob work intermittently or only close to the car?

on May 22, 2026

Car electronics

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What do the letters on a voltage regulator mean (e.g., 7805 vs 78L05 vs 78M05)?

on May 21, 2026

Electronic Components

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How do I test if a component is bad (without fancy equipment)?

on May 21, 2026

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Garage Circuits

Welcome to Garage Circuits — a place where curiosity meets hands-on electronics. This blog is dedicated to DIY electronics, practical projects, and real-world circuit design that you can build yourself. Whether you're just starting out or already deep into the world of resistors, microcontrollers, and oscilloscopes, you'll find something useful here.

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Arduino
Battery
BGA reflow reballing
CAD
Capacitors
Car electronics
Circuit
Circuit Simulator
Computers
Electronic Components

Electronics repair
LED diode
Measuring
Power Supply
PWM speed controller
Soldering
Transistor

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How do I know if my component is dead (diode, transistor, capacitor)?

Short Answer: Use a multimeter’s diode/continuity mode. Detailed: Diode – Should show ~0.6V one way, open circuit (OL) the other. BJT transistor – Measure base-emitter and base-collector like two diodes. Capacitor – Set to ohms; it should start low (charging) then go to infinite. If it reads short (0Ω) or stays low, it’s dead. For electrolytics, look for bulging top or leaked electrolyte. Figuring out if a component is dead comes down to measuring how it behaves vs. how it should behave . A multimeter is usually enough for quick checks. 🔧 1. Diode test ✅ What a good diode does Conducts in one direction (forward) Blocks in the other (reverse) 🧪 How to test Set multimeter to diode mode Measure both directions 📊 Results Forward direction: ~0.6–0.7V (silicon diode) Reverse direction: OL / no conduction ❌ Bad diode signs 0V both ways → shorted OL both ways → open (dead) ⚡ 2. Transistor (BJT) test Think of it as two diodes back-t...

Getting started with BGA (Ball Grid Array) reflow and reballing

Getting started with BGA (Ball Grid Array) reflow and reballing is a great skill if you're into electronics repair (especially GPUs, consoles, and laptops). But it’s also one of the more demanding areas of soldering—so starting with the right mindset and tools matters a lot. 🔧 What You’re Actually Doing Reflow : Heating the existing solder balls under a chip until they melt and reconnect. Reballing : Removing the chip, cleaning it, and applying brand-new solder balls before reinstalling. 👉 Reflow = quick fix (sometimes temporary) 👉 Reballing = proper repair 🧰 Essential Equipment 1. BGA Rework Station Hot air + bottom heater combo Examples: brands like Quick , ATTEN Budget option: IR (infrared) stations (less precise) 2. Hot Air Station Needed even if you have a full rework station Look for stable airflow + accurate temp control 3. Preheater (VERY important) Prevents PCB warping Ensures even heating 4. Stencils (specific to chip model) Use...

Can I Measure Current by Putting My Multimeter Probes Across a Component?

You want to measure how much current a device is using. You have a multimeter. You know that to measure voltage, you put the probes across (in parallel with) the component. So for current, you do the same thing, right? Wrong. And this mistake blows more multimeter fuses — and destroys more meters — than any other. If you're lucky, you'll just hear a small pop and your meter will stop working on the current ranges. If you're unlucky, you'll see sparks, smell smoke, and possibly damage the circuit you're testing. The Short Answer No. Never measure current by putting probes across a component. Current is measured with the meter in series with the circuit — meaning all the current must flow through the meter. Putting probes in parallel creates a short circuit across the power supply. Why This Mistake Is So Dangerous What Happens Inside Your Meter On voltage settings (V~, V⎓), your multimeter has very high resistance — ...

How do I identify an unknown component?

Short Answer: Use a combination of visual markings , multimeter tests , and context (where it came from and what it connects to). Detailed: Unknown components appear in junk drawers, salvage boards, and mystery bags. Here's a systematic approach: Component type How to identify Resistor Color bands (axial) or numbers (SMD). Measure with multimeter. Capacitor Shape (cylinder = electrolytic, disc = ceramic), markings (µF, nF, pF), polarity stripe Diode Cylinder with stripe (cathode), two leads. Diode mode on multimeter → 0.6V one way Transistor Three leads, TO-92 (plastic) or TO-18 (metal can) package. Diode mode test between leads IC (chip) Part number printed on top. Search " [part number] datasheet" Inductor Usually green/blue epoxy-coated or toroidal (donut-shaped). Low resistance (1–50Ω) Transformer Multiple pins, copper windings visible, low DC resistance on primary/secondary LED Clear or colored lens. Diode mode → some glow dimly Switch Mechanical clicks, continuit...

Flux and Soldering: The Secret Weapon for Perfect Joints Every Time

You've seen it happen. You touch your soldering iron to a joint, and the solder just... sits there. It balls up. It refuses to flow. The joint looks dull and crusty. Then you watch an experienced technician. They touch the same joint, and solder flows like water — smooth, shiny, perfect in one second. The difference? Flux. Flux is the single most underrated tool in electronics soldering. It fixes bad joints, cleans oxidized surfaces, and makes soldering easier for beginners and pros alike. In this guide, you'll learn: What flux actually does (it's not magic — it's chemistry) The 4 types of flux and when to use each How to apply flux like a pro How to clean it (or not — depending on type) Why "no-clean" flux sometimes still needs cleaning What Is Flux — And Why Do You Need It? Short answer: Flux removes oxidation from metal surfaces, allowing solder to wet (stick to) and flow properly. The longer answer: When metal is exposed to air, it forms a thin oxide l...

Why do swollen capacitors kill electronics?

Short Answer: Swollen electrolytic capacitors lose capacitance and increase equivalent series resistance (ESR), causing voltage ripple that confuses or damages circuits. Detailed: Electrolytic capacitors dry out over time. Signs of failure: Bulging top (pressure vent pushed outward) Leaking brown/black electrolyte Rust-colored residue on circuit board Effects on circuit: Symptom What's happening Device randomly restarts Voltage drops below regulator threshold Loud buzzing from speakers Power supply ripple LCD flickering Unstable backlight voltage Device works cold, fails hot ESR increases with temperature Fix: Replace all capacitors of the same series (not just the swollen one). Use low-ESR, 105°C rated caps for power supplies.

Can I fix a device with a cracked screen without replacing the whole screen?

Short Answer: For glass-only cracks (LCD working underneath) — yes with LOCA glue. But it's hard. For most people, replace the whole display assembly. Detailed: Screen damage falls into two types: Damage LCD working? Repair possibility Glass only (cracked but image fine) Yes Glass-only replacement using LOCA (UV glue) — advanced skill LCD cracked (black spots, bleeding colors) No Must replace LCD + glass as assembly Glass-only repair (hard, 50% success rate for beginners): Separate glass from LCD using heat plate (70°C) and thin wire Remove old LOCA glue with solvent Apply new LOCA glue Align new glass perfectly Cure with UV lamp (not sunlight) Easier approach for most people: Buy "screen assembly with frame" (LCD + glass + frame pre-assembled) — 20 – 80 f o r p h o n e s , 20–80 f or p h o n es , 40–150 for tablets Transfer small parts (speaker mesh, front camera bracket) Swap in one piece Pro tip: On iPhones and Samsung phones, the screen is g...

Why does my cruise control work intermittently or not at all?

Intermittent cruise control isn’t random—it usually means one of the systems it depends on is giving inconsistent signals. Cruise control ties into brakes, speed sensors, engine controls, and safety systems, so even a small fault can disable it. Here are the most common causes: 🚗 1. Brake light switch (top culprit) Cruise control shuts off the moment you touch the brake. If the switch is faulty or misadjusted, it may think you’re braking when you’re not. Clues: Cruise won’t set at all Or it drops out suddenly Brake lights may flicker or stay on ⚡ 2. Wheel speed sensor / ABS issues Cruise relies on accurate speed data. A failing sensor sends inconsistent readings. Clues: ABS or traction control light is on Speedometer behaves oddly 🧠 3. Faulty steering wheel controls or clock spring The buttons on your steering wheel send signals through a clock spring. Wear or damage can cause intermittent contact. Clues: Buttons only work sometimes Horn...

Why does my soldering iron tip turn black and not melt solder?

Short Answer: The tip is oxidized — you've been running it hot without keeping it tinned with fresh solder. Detailed: A soldering iron tip is copper plated with iron. At high temperatures (350°C+), exposed iron reacts with oxygen to form black iron oxide. Solder won't wet (stick to) oxide. Prevention: Always keep a small blob of solder on the tip when idle Use brass wool (not a wet sponge — thermal shock cracks tips) Set temperature to 300–330°C for leaded solder, 350–380°C for lead-free Fix (if not pitted): Clean with brass sponge Apply fresh rosin-core solder Wipe on damp sponge (quickly) Repeat until solder flows evenly If tip is pitted or has holes: Replace it. Tips are consumables ($2–10).

Help Choosing a Simulator LTspice, QSPICE or TINA-TI

Choosing between LTspice, QSPICE, and TINA-TI is less about “which is best” and more about what kind of circuits you simulate and how you like to work . Here’s a clear, practical breakdown 👇 ⚔️ LTspice vs QSPICE vs TINA-TI Feature LTspice QSPICE TINA-TI 💰 Price Free Free Free 🧠 Difficulty Medium Medium Easy ⚡ Speed Very fast Extremely fast (new engine) Good 🧰 Models Huge (Analog Devices + community) Growing Strong for TI parts 🎛️ UI Old-school Modern-ish Most beginner-friendly 🔬 Analog simulation Excellent Excellent Good 🤖 Digital / mixed Limited Better than LTspice Better GUI tools 📚 Community Massive Small (new) Smaller 🟢 LTspice — The Safe Default Why it dominates: One of the most widely used SPICE tools Extremely fast and stable for analog simulation Huge library + tons of tutorials 💡 Best for: DIY electronics (perfect for your Garage Circuits blog) Power supplies, amplifiers, PWM, analog circuits ⚠️ Downsides: Interface feels outdated Dig...

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