Position: Index > Control Circuit >

The principle of large capacitors charge controller

2015-03-02 07:30  
Declaration:We aim to transmit more information by carrying articles . We will delete it soon, if we are involved in the problems of article content ,copyright or other problems.


This article describes a large capacitor charge controller works. The principle is simple there, we recommend that combine text carefully read the complete schematic. To better grasp this principle, it is recommended to read several times on this principle.

Note that when the circuit is open, and a high current draw starts dicharging the capacitor, T1 (N-MOS with low channel resistance – IRF1010, IRFP054 , IRF048, P60N06 etc) is actually conducting in reverse direction (as in syncronous rectifiers: S->D not D->S). This is OK for a fully open MOS FET. The circuit could be built on P-channek devices too but they are inherently worse conductors than N-channels.Such a cheap, simple circuit needs no heatsink. Just parallel as many FETs as necessary (with a common gate control network). Given amplifier (AB class) useful output P /Watts/ and each FET’s Rds /Ohms/, and 1 Watt maximum heat dissipation for each, number of transistors N>=1/6 * P * sqrt (Rds). Practically, it is safe to cut N 2-3 times, so minimum N>=1/15 * P * sqrt(Rds). That is, one IRF1010 with maximum (hot) Rds of 0.020 Ohms, can safely serve a 120W output amplifier. Commercial controllers rely on many (some as many as 18 devices) small dirt-cheap transistors in D2 or MiniDIP cases, each dissipating up to 0.3-0.5W. Some of them have Rds actually better than the best devices in ‘large’ TO220 and TO247 cases.A step further is to disable capacitor discharge when REMOTE control signal is low. The simplest solution is to power all gate control circuitry from the REMOTE wire, or – better – with a follower. LEDs D3-D4 indicate charge, D5-D6 – switch is open. 0.2F capacitor value shown is for example only – that’s enough assuming a single transistor serves a 120W amp.


This article describes a large capacitor charge controller works. The principle is simple there, we recommend that combine text carefully read the complete schematic. To better grasp this principle, it is recommended to read several times on this principle.VN:D [1.6.9_936]

 


Reprinted Url Of This Article:
http://circuits.radio-electronics.co/cars-motorcycles/large-capacitor-charge-controllers/