Instrument Light Dimmer

400Hz pulse output, Load 3amp

 

Comments

A 0.1 uF cap in parallel with C3 for high -freq. noise suppression.
Big fat toroid and caps upstream for the same reason - if needed.
Stuffing option on a low value cap from FET gate to ground for EMI and noise reduction. You can slap the FET on REAL HARD, but unless transition losses are high (heatsink?), 300 Hz is almost static. Soften the ON-OFF edges a little.
Listen and try, say about 33 -200 pF.
Otherwise, good ckt.
john linstrom
Sunspot Svcs.

 Part list    Descriptions   Mouser part     _numbers 
Case Bud (nema 4) Mfgr. Part#: AN-1301   Mouser# 563-AN-1301 563-AN-1301 
U1 LM555 DIP-8 SINGLE TIMER; Mfgr. Part#: LM555D  Mouser Part#: 513-NJM555D 513-NJM555D 
T1 IRF520; Mfgr. Part#: IRF520_R4941 TO-220AB N-Ch Power  Mouser Part#: 511-IRF520 511-IRF520 
C1 0.15mf cap Metallized Polyester Film Capacitor; Mfgr. Part#: MKT1817415064   Mouser Part#: 75-MKT1817415064 75-MKT1817415064
D2 1N6278; Surge Suppression General Semi Transient Voltage Suppressors GP-20 1.5KW 20V Mouser Part#: 625-1.5KE20A    Mouser Part#: 75-MKT1817415064 625-1.5KE20A 
R4  Power Resistors 0.15ohm 5W ; Xicon 5W 5% Cement Power Resistors PWR 5W 0.15  Mfgr. Part#: 280-CR5-0.15 280-CR5-0.15 
R3 Potentiometer SPDT 25K ; Xicon/Alpha 24mm Carbon  Mfgr. Part#: 315-2415-25K 315-2415-25K 
C3 35V 2200uF 20% Mfgr. Part#: 140-XAL35V2200   140-XAL35V2200 
R2  1Kohm 1/4W 1% Metal Film Resistor; Mfgr. Part#: 271-1K Xicon 271-1K 
R1 510 ohm 1/4W 1% Metal Film Resistor ; Mfgr. Part#: 271-510 Xicon 271-510 
C2 500V 1nF Y5U/11 20%; Mfgr. Part#: 5SQ102MOAAM 5SQ102MOAAM 
D3 1N4148 ; Mfgr. Part#: 1N4148   Mouser Part#: 78-1N4148 78-1N4148
D1 1N4002 ; ( DO-204AL 1.0A 100V ) Mouser Part#: 625-1N4002 625-1N4002 
  HEAVY DUTY 4 POS ;  ; Mfgr. Part#: 1437664-6 Tyco/Buchanan Terminal Blocks HEAVY DUTY 4 POS   Mouser Part#: 571-14376646 571-14376646 

 

    Parts available at  www.mouser.com  

 

 

 

Light dimmer with current limit and noise suppression

(not tested)