Flyback Diode Replacement Inquiry

flux

For 24 V DC solenoid valves with 2 to 4 hour energized periods, my best recommendation is to stay with a mechanical PCB relay like your current K1, provided the valve current is within the relay's DC rating.
My recommendation

Table

ChoiceVerdictWhy
K1Good default choiceDatasheet says 7 A at 28 VDC for Form C resistive load, 30 VDC max switching voltage, 10 A max switching current, and 0.36 W coil power
HLS8L-DC5V-S-CStronger upgrade candidateDatasheet says up to 15 A max switching current, 30 VDC max switching voltage, 100,000 electrical ops, coil options 0.36 W or 0.45 W
PR2-5V-450-1CPossible, but I would not pick firstI could confirm 5 V coil and 450 mW coil power, but I could not reliably retrieve the full contact/life data from the datasheet source
Best pick
  • If your valves draw modest current and cost/availability matter, keep using K1.
  • If you want more switching margin, I would choose HLS8L-DC5V-S-C.
Important caveat
A 24 V solenoid valve is an inductive DC load, so the key spec is not just voltage, but the valve's steady-state current and ideally the relay's DC inductive load rating. The datasheets I checked clearly give general/DC max ratings, but not a clean valve-specific inductive rating.
For an 8-channel board
If you use 8 relays like K1, the relay coils alone dissipate about 2.88 W total, so thermal buildup and 5 V supply sizing matter.
What I need from you to choose confidently
  • Valve current at 24 V
  • Whether the valve is DC or AC only
  • Whether fast release is important
  • Whether you want lowest cost or highest reliability margin
If you give me the solenoid valve current, I can tell you which of these is the better relay.
Check K1 rating
Find stronger relay
Review flyback needs
Size coil supply
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INDICATOR LED
INPUT
VCC
VCC
Q1
Manufacturer Part Number
BC847,215
R3
Resistance
200 Ω
K1
Manufacturer Part Number
SRD-05VDC-SL-C
J1
D1
Manufacturer Part Number
1N4148WS-7
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5V Relay Modular

5V Relay Modular thumbnail
5V relay re-usable, modular, a sub-layout. This project is a dedicated design for a compact and reliable 5V relay module engineered to safely switch higher-power loads using a logic-level 5V control input. It features robust electrical performance with an integrated opto-isolator that provides essential isolation and protection between control circuitry and the relay output, ensuring enhanced stability and reduced electrical noise. This is ideal for seamless integration with microcontrollers in automation, control systems, and various embedded applications. Optimized for manufacturing-ready PCB layouts, this reliable module is perfect for prototyping and production in modern electronics projects.
#5Vrelay #relaymodule #electronics #PCBdesign #automation #embeddedprojects #module #sublayout

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