- RADIOSOL how to solder: The RDA5807 FM radio kit builds from lowest to tallest components in a fixed order.
- Key rule: Apply a small solder blob to one pad first to "tack" chips and modules in place.
- Polarity matters: Electrolytic capacitors and LEDs go long lead (positive) into the "+" marked hole.
- Chip orientation: Match the notch on ICs (TDA2822, STC8G) to the notch on the socket.
- Final step: Never power the radio with USB and batteries at the same time.
Before You Solder: Kit Overview and Preparation
The RADIOSOL RDA5807 soldering kit turns a set of through-hole components into a fully functional FM radio with a four-digit digital tube display, station memory, and adjustable volume. Success depends on installing parts in the right order and using the "tack solder" positioning technique for multi-pin parts.
Video Highlights:
- Full 23-step build of the RADIOSOL RDA5807 FM radio kit
- Tack-solder technique for the AMS1117 regulator and RDA5807 module
- Correct polarity for electrolytic capacitors, LED, and speaker wiring
- Battery contact and back-cover assembly with red/black wiring
- Power-on test and troubleshooting advice
The kit's main components and their positions are summarized below:
| Component | Position | Key Installation Note |
|---|---|---|
| AMS1117 voltage regulator | Top of board | Tack-solder large pad first, then remaining pins |
| RDA5807 radio module | Module footprint | Square part faces down, cylindrical part faces up |
| USB socket | DC power | Solder top first, flip board for remaining pins |
| Resistors | R2–R16 | Match color bands; R6 sits apart, near USB connector |
| Ceramic caps (104) | C1, C2, C6, C9 | 100 nF, no polarity |
| Electrolytic caps | C3–C8, C9 area | Long lead = positive into "+" hole |
| TDA2822 amp + STC8G MCU | U9 and U2 sockets | Notch on chip matches notch on socket |
| Digital display, switches, antenna | Top side | Match decimal points; solder antenna vertically |
Sort and identify every component before touching the iron. Group resistors by color band, and confirm capacitor values against the PCB silkscreen so you never have to desolder a misplaced part.
RADIOSOL How to Solder: Core Technique
Good solder joints on the RADIOSOL board come down to three habits: tinning one pad for positioning, heating both the pad and the lead, and trimming excess leads after each stage.
Tack the part in place
Apply a small amount of solder to one pad, then position the component while the solder is molten. This holds chips, modules, and sockets steady for the remaining joints.
Solder the remaining pins
Heat each pad and lead together for about a second, then feed in solder. Joints should be shiny and cone-shaped, not dull or blobby.
Trim excess leads
After each component group, clip leads flush with cutters. Trimming as you go keeps the board clean and prevents short circuits.
| Solder Joint Problem | Likely Cause | Fix |
|---|---|---|
| Dull, grainy joint | Iron too cold or moved while cooling | Reheat and add a touch of solder |
| Blob that doesn't wet the pad | Dirty tip or insufficient heat | Clean tip, retin, reheat both pad and lead |
| Bridge between pins | Too much solder | Use desoldering braid, then redo the joint |
| Radio works intermittently | Cold joint on module or socket | Press-test joints and reflow suspicious ones |
Support the board, never hold components by their body while soldering, and keep the iron in its stand when idle. Ventilate your workspace and wash hands after handling solder.
Component Installation Order
Follow the build order exactly. Installing tall parts first makes it hard to solder low-profile parts flat afterward.
Stage 1: Chips and Sockets
- AMS1117 regulator (tack-solder first)
- RDA5807 module, square side down
- USB socket at DC power
- 8-pin and 16-pin IC sockets, notch aligned
Stage 2: Passives and Controls
- 10 kΩ at R16, 1 kΩ at R2–R6
- 510 Ω at R7–R14
- Ceramic 104 caps at C1, C2, C6, C9
- 200k potentiometer at R1, LED at D1
Stage 3: Tall Parts and Wiring
- Electrolytic caps at C3–C8 (watch polarity)
- Digital display, matching decimal points
- Tact switches S1–S4, antenna vertical
- Chips into sockets, notches aligned
Two placement traps catch many builders:
| Trap | Details |
|---|---|
| R6 location | Not next to R2–R5; it sits farther left, near the USB connector |
| C8 location | Higher on the PCB, between a ceramic capacitor and the 16-pin socket |
| LED at D1 | Long lead is positive; verify before soldering |
| Display orientation | Match decimal points on the display to those on the PCB |
The long lead of every electrolytic capacitor is positive and the short lead is negative. Insert the long lead into the hole marked "+" on the PCB—reversed capacitors can fail or damage the circuit.
Final Assembly: Case, Battery, and Speaker Wiring
With the circuit board finished, the build moves to the enclosure. Correct battery contact placement and color-coded wiring determine whether the radio powers on.
Install battery contacts
Spring contacts are negative; flat contacts are positive. Seat all four contacts with mounting tabs facing down, then bend the long contacts' tabs to lock them in.
Wire the contacts
Tin the two short contacts, solder the red wire to positive and black to negative, then route both wires through the side grooves and solder them to the BAT pads (red to +, black to −).
Wire and seat the speaker
Solder red/black wires to the speaker terminals, connect the other ends to U8 matching polarity, place the speaker in its slot, and press the board into the case slots.
Test and close up
Insert three AAA batteries (negative to spring) or use USB power, adjust the potentiometer for volume, then power off, install the cover and buttons, and reinstall batteries.
| Power Option | Setup | Caution |
|---|---|---|
| 3x AAA batteries | Negative terminal against each spring contact | Reinstall only after final assembly |
| USB cable | Connected to the DC USB socket | Never combine with batteries |
Do not use USB power and batteries at the same time. Choose one power source before testing.
Testing and Troubleshooting
If everything is assembled and soldered correctly, the radio powers on and automatically begins searching for FM stations. Use this checklist to verify your build before and after closing the case.
Build Verification Checklist:
- All resistor positions match their color bands (R2–R16)
- Electrolytic capacitors and LED installed with correct polarity
- IC notches aligned with socket notches on TDA2822 and STC8G
- Display decimal points matched to PCB markings
- Red/black wires connected to matching positive/negative terminals
- Only one power source active (batteries or USB, never both)
Common fixes for a non-working radio:
| Symptom | First Check | Solution |
|---|---|---|
| No power on | Battery orientation | Try fresh AAA batteries or a different USB source |
| Weak or no audio | Speaker wiring at U8 | Verify red to positive, black to negative |
| Display issues | Display orientation | Confirm decimal points align with PCB markings |
| Random behavior | Cold solder joints | Inspect and reflow all joints, especially module pins |
A correctly assembled RADIOSOL RDA5807 radio powers on, displays the tuned frequency on the digital tube, and auto-scans for stations on first boot.
FAQ
Q: What is the easiest RADIOSOL how-to-solder technique for beginners?
Use the tack-solder method: melt a small blob of solder onto one pad, hold the component in place while it cools, then solder the remaining pins. This keeps chips, modules, and sockets perfectly aligned.
Q: Why won't my radio turn on after assembly?
First try fresh AAA batteries or a different USB power source. If the problem continues, inspect every solder joint—one or more connections may not be making proper contact, especially on the RDA5807 module and battery wires.
Q: How do I know which way to insert the TDA2822 and STC8G chips?
Slightly bend the pins so they are perpendicular to the chip body, then insert each chip into its socket with the notch on the chip facing the notch on the IC socket.
Q: Can I power the radio with USB while batteries are installed?
No. Never use USB power and batteries at the same time. Pick one power source, and reinstall batteries only after the final assembly is complete.