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home | newest check | boards | help index | log | ps | userlogin | send sysop | slog | status forward | bcm news | users | version | remove cookieG8MNY > TECH 14.03.26 19:03l 125 Lines 6292 Bytes #7 (0) @ WW BID : 54384_GB7CIP Subj: A Common High Current PSU Path: JH4XSY<N3HYM<GB7YEW<GB7CIP Sent: 260314/1000Z @:GB7CIP.#32.GBR.EURO #:54384 [Caterham Surrey GBR] From: G8MNY@GB7CIP.#32.GBR.EURO To : TECH@WW By G8MNY (Updated Aug 22) (8 Bit ASCII graphics use code page 437 or 850, Terminal Font) This is a simple & therefore reliable common design used on commercial PSU. e.g. TRIO PS30 & ICOM PS55. Component values differ slightly between models. HOW IT WORKS The rectifiers charge up C1 to 25V. R3 puts some voltage on the output (>1.5V), a fraction of this turns (pot arm) on Q2 (0.5V on Q2 base). This turns on Q1 that drives the 2 large high current power pass Transistors T1 & 2. When the output voltage is >10V the zener conducts turning off Q2 as it pulls up the emitter voltage compared to Q2's base on the VR1 pot output fraction setting. ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾄﾄﾂﾄﾄ2R2ﾄﾂﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ ｳ +19-25V ｳ 4m7ｳ+ R1 +ｳC3 4K7 ｳ/e TIP _ｳ_ _ｳ_ === === ﾃﾄﾄﾄﾄﾄﾄﾄﾄｴ Driver /_\ /_\ C4ﾃﾄﾄﾄﾄﾄﾄﾙ4m7 ｳ Q1ｳ\ 2SD596 ｳD1 ｳD2 ｳ +15-25V ｳ ｳ ｳ ﾉﾍﾍﾍﾍ)ﾍﾍﾍﾋﾍﾍ)ﾍﾍﾍﾑﾍﾍﾍﾍﾍﾍﾍﾍ)ﾍﾍﾍﾍﾋﾍﾍﾍﾍﾍ)ﾍﾍﾍﾍﾍｻ 2x TO-3 ｳ / \ ｳ ｺ ｳ ｳ ｳ \ｳ ｳ ｳ/ Fan Cooled AC_ｳ_/' B1`\_ｳAC ｺ ｳ R3 ｳ T2ﾃﾄﾄﾄﾁﾄﾄﾄｴT1 & Insulated ~ ｳ \ / ~ ｺ ｳ 56R ｳ e/ｳ 2x ｳ\e on Heatsink ｳ `\ /'35A ｺ ｳ ｳ ｳ ｺ 2SD797 ｺ ｳ ｺ Bridge ｺ ｳ ｳ ｳ R8 R7 L _ｳ_ ｺ ｺ ｳ ｳ ｳ 0R05 0R05 20A E \_/ ｺ ｺ ｳ ﾃﾄﾄﾄﾄﾄﾄﾄﾄ)ﾄﾄﾄﾄﾊﾍﾍﾑﾍﾍﾍﾍﾍﾍﾍﾍﾊﾍﾑﾍﾍﾍﾑﾍﾍo--oﾍﾍﾍ>+13.8V D ｳD2 ｺ 68mF ｺ+ ｳ R6 1K8 ﾃﾄｿ ｳ ｳ ｳ @ 20A _ｳ_ ｺ C1 === ｳ ｳ Q2ｳ/ ｳC7 _ｳ_D3 R9 ｳ D4\_/ ｺ 25V ｺ ｳ 500R<ﾄﾄﾄﾄｴ === '/_\10V 220R ｳ+ ｳ ｺ ｺ ｳ POT VR1 ｳ\e ｳ10n ｳZener ｳ ===C5 390R ｺ ｺ ｳ ｳ ﾀﾄﾁﾄﾄﾂﾄﾄﾙ ｳ ｳ4m7 ｳ ｺ ｺ ｳ R5 820R R4 120R ｳ ｳ E>ﾍﾏﾍﾍﾍﾍﾊﾍﾍﾍﾍﾍﾍﾍﾍﾊﾍﾍﾏﾍﾍﾍﾏﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾏﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾏﾍﾍﾍﾏﾍﾍﾍﾍﾍﾍﾍﾍ>-VE Some of the reference numbers are repeated as components are on different PCBs. AC The mains transformer is a conventional (not toroidal) type 17V @ 26A (2x 13A) for the 20A rated PSU. The high pulse current AC wiring to the bridge & to the reservoir C, are in thick & twisted wire to keep the losses & magnetic pulse radiation down. A slow blow mains fuse of 6A is used. PSU FEATURES It has 2 power rails, this is because the bridge rectifier & capacitor losses under heavy load can give the driver's supply up to 1V more. This allows for better peak drive current when it is needed. The 2R2 limits the drive current when C5 is exhausted allowing for higher peak currents than the steady rating, but this current limiting is very dependent on the mains voltage! Current "Foldback" is provided with reference zener D3 fed from the output. The start up current comes from the R3 56R, & R9 220R is the minimum discharge load. A quiet thermally switched DC cylinder fan comes in when the heatsink is at a scalding 60. On the ICOM unit, the mains is remotely switched on the rig with the same lead as the high current DC output. Polarity of the plug is "VERY CRITICAL", as if it is forced to accidentally connect upside down, (not easy to do) live mains will flow to the +ve DC side of your Rig! (it may be safer to remotely switch neutral as that current would be lighter!) OTHER LIMITATIONS There is no rig protection from a shorts of T1/2 pass transistors & 25V output will damage your rig! ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄｿ Leads ｳ ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ ｳ ﾅﾄﾄ Fuse ｳ|P ｳ Cap ｳ ｳ F ﾅﾄﾄ ｳ| ﾀﾄﾄﾂﾄﾄﾄﾄﾂﾄﾙ ｳ ﾅﾄﾄ ｳ|C /ｳ ｳ\ ｳ A ﾅﾄﾄ Bridge ｳ| ｳ ｳ ｳ ｳ ｳ ﾅﾄﾄ ｳ|B ｳ ｳ ｳ ｳ ｳ N ﾅﾄﾄ 2x T03 ｳ \ｳ ｳ/ ｳ ﾅﾄﾄ ﾀﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾁﾄﾄﾄﾄﾁﾄﾄﾄﾄﾙ MODIFICATIONS. I have done to my ICOM one.. 1/ Heatsink added to Q1 & bolted flat to PCB location provided. 2/ Blackened main T1 & T2 heatsink, so the thermal controlled fan runs less. 3/ Fused added on T1 & T2 emitters on PCB tags (13A ones soldered in). 4/ Squeezed in more main smoothing 2x 33mF @25V for /P work with poor AC power. 5/ Proper current limiting (@ 15A/transistor) with 2 extra PNPs Q3 & Q4. These will also shut the PSU down if a 13A fuses blows. 6/ Removed the 2R2 the old current limiting method, to gain more output current drive when the AC supply is poor. 7/ Changed D1 & 2 for lower voltage drop BYW29, for when the AC supply is poor. 8/ Added an output overvoltage protection zener (like an SCR Crowbar). 9/ Larger output Cap (10mF 16V) wired across PCB output tags. 10/ Mains Transformer tuned (PF=1) for /P work with 1uF 250VAC. 11/ Added a trip switch fuse low current output, for accessories. 12/ Added Battery "crock leads" & 30A trip. ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾄﾄﾂﾄﾄﾄﾂﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿ ｳ +18-25V ｳ 4m7ｳ+ +ｳ4m7 4K7 ｳ/e TIP Driver _ｳ_ _ｳ_ === === ﾃﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｴ on Heatsink /_\ BYW29 /_\ C4ﾃﾄﾄﾄﾙC5 ｳ Q1ｳ\ ｳD1 ｳD2 ｳ+15-25V ｳ ｳ 2x TO-3 ｳ ﾉﾍﾍﾍﾍ)ﾍﾍﾍﾋﾍﾍ)ﾍﾍﾑﾍﾍﾍﾍﾍﾍ)ﾍﾍﾍﾍﾋﾍﾍﾍﾍﾍﾍﾍﾍﾍ)ﾍﾍﾍﾍﾍﾍﾍﾍﾍｻ Mounted on ｳ / \ ｳ ｺ ｳ ｳ ｳ \ｳ ｳ T2ｳ/ Blackened Fan ACｳ_/' B1`\_ｳAC ｺ ｳ R3 ｳ T1ﾃﾄﾄﾄﾄﾄﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄｴ Cooled Heatsink ~ｳ \ / ~ ｺ ｳ 56R ｳ e/ｳ ｳ\e ｳ `\ /'35A ｺ ｳ ｳ ｳ ﾇﾄﾄﾄﾂﾄﾄﾄｿ 1nﾚﾄﾄﾄﾂﾄﾄﾄｶ ｳ ｺ Bridge ｺ ｳ ｳ ｳ ｺ eｳ === === ｳe ｺ ｳ ｺ + ｺ ｳ ｳ ｳ Fuse \ｳ ｳ1n ｳ ｳ/ Fuse Rig ｳ ﾌﾍﾍﾍｵﾆﾍﾍﾍｹ ｳ ｳ ｳ ｺ Q3ﾃﾄｴ ﾃﾄｴQ4 ｺ ﾉﾍﾍﾍﾍﾍ>+13.8V L_ｳ_ ｺ 33mF ｺ ｳ ｳ ｳ 0R05 /ｳ1K5 1K5ｳ\ 0R05 ｺ @20A E\_/� ｺ + ｺ ｳ ﾃﾄﾄﾄﾄﾄﾄ)ﾄﾄﾄﾄﾊﾍﾑﾍ)ﾍﾍﾍﾏﾍﾍﾍﾏﾑﾍﾍ)ﾍﾑﾍﾊﾍﾍﾑﾍﾍﾍﾍﾍﾑﾍﾍｹ 2A D ｳ ﾌﾍﾍﾍｵﾆﾍﾍﾍｹ ｳ 1K8 ﾃﾄｿ ｳ ｳ ｳ ｳ ｳ ｳ 10mFｳ+ ﾇﾄo-oﾂ>+13.8V _ｳ_ ｺ 33mF ｺ ｳ ｳ Q2ｳ/ ｳ _ｳ_ﾀﾄﾄﾄﾄﾄﾂﾄﾄ)ﾄﾄﾙ ｳ _ｳ_ === ｺ ﾀ> 2A \_/ ｺ ｺ+ ｳ 500<ﾄﾄｴ === '/_\ ｳ ｳ +ｳ '/_\ 16Vｳ ｺ 30A D4ｳ ｺ C1 === ｳ POT ｳ\e ｳ10n ｳ 10V ｳ R9 === ｳ17V ｳ ﾈﾍo-oﾍ<>Batt+ 390R ｺ 68mF ｺ ｳ ｳ ﾀﾄﾁﾄﾂﾄﾄﾁﾄﾄﾄﾄﾄﾄﾄﾙ 220R ｳC5 ｳ75A ｳ ﾉﾍﾍﾍﾍﾍ<>Batt- ｳ ｺ ｺ ｳ 820R 120R ｳ ｳ4mF ｳ ｳ ﾇﾄﾄﾄﾄﾄ>Earth E>ﾏﾍﾍﾍﾍﾊﾍﾍﾍﾍﾍﾍﾍﾍﾊﾍﾍﾏﾍﾍﾏﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾏﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾍﾏﾍﾍﾍﾍﾏﾍﾍﾍﾍﾏﾍﾍﾍﾍﾍﾏﾍﾍﾊﾍﾍﾍﾍﾍ>-VE With these modifictions the PS will do 22A @ 13.8V output with 200-240V input. Why Don't U send an interesting bul? 73 De John, G8MNY @ GB7CIP
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