Timed Power Vending Device Prototype
Budget: $750 – $1,500 USD
I need a working proof-of-concept that lets a customer pay, see a quick on-screen confirmation, and then receive mains power for a pre-set period. The heart of the build will be a Raspberry Pi, so all control logic, UI, and connectivity should revolve around that board.
Payment flow
The unit must accept both chip-and-tap credit/debit cards and popular mobile wallets (Apple Pay, Google Pay, etc.). I’m open to any certified payment module you prefer—Square, Stripe Terminal, Adyen, or an SSI-enabled USB reader—as long as it can return an “approved” token that the Pi can consume in under two seconds. Once the transaction clears, the screen must flash a confirmation plus remaining time, then energise the power relay.
Hardware & safety
You’ll design or select a solid-state relay or contactor rated for continuous duty and integrate over-current, temperature, and ground-fault protection. A single IEC or NEMA outlet is fine for the prototype. All enclosure work should follow basic UL/CE guidelines so we can later certify without redesign.
User interface
A small touch or 4-button LCD is enough for now: choose duration, insert/tap card, show countdown. Clean, minimal graphics written in Python (Tkinter, Kivy, or PyGame—your choice). OTA firmware updates via Wi-Fi would be a plus.
Deliverables
• Schematics and BOM (Altium/KiCad)
• Pi image or install script with documented Python code
• 3D model or drawing of enclosure with cut-outs for power inlet, outlet, screen, and reader
• Fully assembled prototype proven to switch 110–240 V AC load for at least three time presets (e.g., 5, 15, 30 min)
• Short video demo and test report confirming payment flow, confirmation screen, and safe shut-off
I’m happy to iterate on component choices, UI flow, and overall design once the basic system operates reliably. If you have past work integrating EMV/NFC readers with Raspberry Pi and can handle both firmware and low-voltage power design, let’s talk.
Payment flow
The unit must accept both chip-and-tap credit/debit cards and popular mobile wallets (Apple Pay, Google Pay, etc.). I’m open to any certified payment module you prefer—Square, Stripe Terminal, Adyen, or an SSI-enabled USB reader—as long as it can return an “approved” token that the Pi can consume in under two seconds. Once the transaction clears, the screen must flash a confirmation plus remaining time, then energise the power relay.
Hardware & safety
You’ll design or select a solid-state relay or contactor rated for continuous duty and integrate over-current, temperature, and ground-fault protection. A single IEC or NEMA outlet is fine for the prototype. All enclosure work should follow basic UL/CE guidelines so we can later certify without redesign.
User interface
A small touch or 4-button LCD is enough for now: choose duration, insert/tap card, show countdown. Clean, minimal graphics written in Python (Tkinter, Kivy, or PyGame—your choice). OTA firmware updates via Wi-Fi would be a plus.
Deliverables
• Schematics and BOM (Altium/KiCad)
• Pi image or install script with documented Python code
• 3D model or drawing of enclosure with cut-outs for power inlet, outlet, screen, and reader
• Fully assembled prototype proven to switch 110–240 V AC load for at least three time presets (e.g., 5, 15, 30 min)
• Short video demo and test report confirming payment flow, confirmation screen, and safe shut-off
I’m happy to iterate on component choices, UI flow, and overall design once the basic system operates reliably. If you have past work integrating EMV/NFC readers with Raspberry Pi and can handle both firmware and low-voltage power design, let’s talk.