GoldPic 3 Pulse Induction Metal Detector

Visitors since : 14th August, 2001

GoldPic 3 is a 'Build It Yourself' pulse induction metal detector design.

Available in semi-kit form, consisting of the following items:

Programmed Microcontroller containing the embedded software

Printed Assembly and User Instructions

Bare Printed Circuit Board

Circuit Schematic

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GoldPic 3 Pulse Induction Features

Fast Response Non-Motion All-Metal Silent Search Mode

Digital processing of the detection signal

Sensitive Analog / Digital Converter

Push Button Threshold Zeroing

Microprocessor Controlled

Liquid Crystal Display

Easy to build & use

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GoldPic 3 Detection Depths

This table shows average detection ranges obtained with the prototypes in air, for a selection of rings and UK and US coins. Detection depths obtained on the beach are typically better than these figures. These depths are using the 7½ inch 27 turn coil. About 20% more depth can be obtained using a 10 inch 20 turn coil, but at the expense of some pin-pointing ability.

Depth (cm) 
Depth (inches) 
Gold Ring (9ct) 21mm x 3.5mm x 1mm
Silver Ring (925) 18mm x 1.5mm x 0.6mm
UK 1p (1996)
UK 2p (1994)
UK 50p (1981)
UK £1 (1983)
US 1c (1972) 
US 5c (1989)
US 10c (1995)
US 25c (1994)
2.8 gm (1/10 oz) Fine Gold Coin
14 gm (1/2 oz) Fine Gold Coin

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The GoldPic Project

GoldPic was in development for 24 months. The third generation design has been extensively field tested on Clifton Beach near Cape Town and is now available in semi-kit form. The machine was designed to detect coins and jewelry on the beach and in shallow water. The timing and circuitry is optimised to detect small items like coins and rings at a good depth.

The development was done as a 'midnight engineering' project. Published designs failed to provide the sensitivity I required to search the soft deep sand on the Atlantic Ocean beaches around Cape Town. The kit is designed to be easy to build, using readily obtainable low cost electronic and mechanical components.

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Assembly and User Instructions

Download the GoldPic 3 Assembly and User Instructions by clicking on the link below. The Instructions contain a full list of the components required and give an idea of the construction skills necessary to successfully build a GoldPic metal detector.

(Requires an Acrobat Viewer)

GoldPic 3 Assembly Instructions (PDF-110K)

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Circuit Schematic

Download the GoldPic 3 Schematic by clicking on the link below. Left-click to view directly in your browser, or right-click to save the file for viewing in a separate graphics application.

GoldPic 3 Schematic Diagram (GIF-112K)

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Ordering Information

SPECIAL OFFER, buy 2 Semi-Kits for $70.00 including postage and packing

ADC0831 A to D Converter ICs available for $3.25

Click here to use PayPal to buy one semi-kit for US $ 42.00

Click here to use PayPal to buy two semi-kits for US $ 70.00

Prices in US $

The semi-kit contains a bare, fibre-glass, tinned, single-sided printed circuit board, the pre-programmed microcontroller integrated circuit containing the embedded software, printed assembly instructions and the circuit schematic. The microcontroller is 'code-locked' to prevent duplication of the firmware.

This is not a complete kit of parts. Other electronic and mechanical components need to be purchased separately in order to complete the construction of your GoldPic metal detector.

View the assembly instructions for the full component list.

This distribution model was choosen as the electronic components can be sourced at prices lower than the South African prices in most other countries. It also reduces the size and weight of the airmail package.

Postal Address:

Trevor R. Hill

2 Jefferson Road


7708, Cape Town

South Africa

Please do not send personal cheques, money orders, postal orders, cashier's cheques or bank drafts, as I cannot cash any of these forms of payment in South Africa.

For further details regarding ordering and payment methods that are suitable, please click on the email link below, add the country you reside in and then send the message:

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Terms and Conditions

DELIVERY Although every effort will be made to dispatch your order within 48 hours of receipt of payment, we cannot guarantee this time scale for all orders. Delivery is via registered airmail unless other arrangements have been agreed on. RETURNS Goods may be returned within 30 days of dispatch for a refund if the printed circuit board has not been soldered on and the goods are still in a saleable condition. In this case the amount paid less 20% (the original packaging / shipping costs) will be refunded. REPAIRS AND PROBLEMS In the rare event that the detector does not function correctly after being assembled, troubleshooting assistance is available via e-mail. In the event that this does not resolve the problem the assembled circuit board may be returned for fault finding and repair. Please obtain confirmation via e-mail before shipping the board back. This service will be provided on a shipping and parts cost basis, i.e. the charge will only be for the return shipping and the components that required replacement. Every effort will be made to resolve the problem but we cannot guarantee success or time scales. LIMITATION OF LIABILITY The supplier shall not be liable in contract, tort, or otherwise, for any loss or damage suffered by the purchaser whatsoever or howsoever arising out of, or in connection with, the supply of goods or services other than to supply goods as described or, at the the supplier's option to refund the purchaser any money paid in respect of the goods. Use of the GoldPic design, Semi-Kit and all related information is entirely at your own risk. In no event shall the supplier be liable for any damages whatsoever.

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On the schematic diagram the 10k resistor across C13 should be labelled R19.

The circuit was designed to provide maximum sensitivity when running from an 8 cell Nicad battery. Some constructors have experienced problems when running from a 12V battery. If you use a 12V lead acid accumulator insert 4 diodes in series with the battery supply to reduce the supply voltage. For an 8 dry (or alkaline) cell battery use 2 diodes. Use 1N4001 silicon rectifier diodes or similar .

Contact Details

Web site and GoldPic created by Trevor R. Hill

Please send queries and comments to me at:


Last revised: Sep 4, 2007.

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