The brightest representative of the different variations of the treatment coil is a version of the PIC controller. It covers about 80% of all the healing frequencies [1,2], allows you to select, configure, and maintain 4 individual treatment programs. The complexity of its manufacture is not much higher than that of the coil with modulation, and the possibility of orders of magnitude more. This version of the coil has a frequency accuracy of modulation is not more than 0.04% over the entire operating range — from 0.1 to 1000 Hz, and is determined by a quartz resonator. The step size is 0.01 Hz in the range 0.1-10 Hz, 0.1 Hz, in the range of 10-100 Hz and 1 Hz in the range 100-1250 Hz. And in increments of 250 Hz it is possible to obtain the maximum possible modulation frequency of 10 kHz. The circuit is powered from any power supply (adapter) with 12V voltage and consumes only 1.2 watts of power.

The heart of this version of the coil is the DD1 microcontroller — PIC16F684. Despite its small external dimensions and relatively low cost, it has fairly broad capabilities: generates a frequency in the range 0.1-10000 Hz, controls the generator field coil on VT1 (modulation) sound signal (BA1) and 4-digit display (HG1). Thus it has low power consumption quartz frequency stabilization (ZQ1) and non-volatile memory. The control scheme of only three buttons — SA1-SA3 (see instruction manual). Work schemes are well documented in previous versions of the medical coil, the difference between this — only modulation control: here she is using a microcontroller.

The following is a list used in the unit circuits, diodes and two modes. In parentheses are possible replacements:

• DD1 — PIC16F684
• DA1 — LM7805 (КР142ЕН5А)
• VT1 — 2SC5200
• HG1 — 4 segment indicator on 74HC555
• BA1 — Active sound emitter voltage is 5V
• ZQ1 — quartz resonator 20MHz
• VD1, VD2 — UF4007
• HL1, HL2 — any led voltage is 3V and the power below 1W
• SA1-SA3 — any push-buttons
• L3 — Choke on 220мкГн, calculated for a current below 0.5 A
• XS1 — any connector for Your adapter to 12V

All capacitors circuits — ceramic or polypropylene, with a nominal value of deviation of no more than 5%. Any low power resistors with a nominal deviation of not more than 20%. The coil itself (L1, L2) is wound in any of the ways suggested here or here.

About how it is stitched, read the article: "Flash PIC controller is just". User management to the coil, see here.

For coil Assembly will fit a small plastic box: with a window under an indicator or with a transparent top. Box of metal — not suitable! The scheme is simple, so her details can be placed on the breadboard. The transistor VT1 must be installed on a small heatsink. Some of the Assembly steps shown in the following photo:

If the circuit is assembled correctly and the microcontroller stitched, the entire coil starts working immediately without configuring. The only thing that you need to adjust the current from the power source. It is adjusted by trimming resistor R1 should be about 100mA at the maximum frequency on the display.