Search results

RF Parts Company ~ Filament & Low Voltage Transformers

X2... :-)

You didn't, you calculated the value at 6.7 ohms which would be for each filament needing 3 amps, not 0.6 amps.

The result is in farads. For the 33.33 ohm impedance it would be approximately 80 uF.

Your math is correct if the filament current is 3 amps... If the filaments need 0.6 amps as you stated just before the 3 amp statement, then R = 33.33 ohms at 12 W.

You are going to need to either measure the filament current or look up the filament current specification and go from there. The resistor size would be equal to: R = 20V/Current in Filaments assuming your series connection and the resistors power rating is equal to I^2*R If it were me, I...

The current knob is a set-point, limit or threshold level. Once the load starts to draw more current than the set-point, the power supply will typically start to lower the output voltage in an effort to reduce power ratings.

There may be extra base drive due to low sniffer/base drive impedance. The OP could disconnect or add the various suspect parts, based on the scenarios we talked about, to troubleshooot... :-)

A relay is really nothing more than an electro-magnet. So when a strong RF field is induced into the keying circuit via the antenna, the RF from the relay contacts can be coupled into the inductive part of the coil which is tied to a capacitor tied to ground. The capacitor tied across the...

Yeah, the collector voltage could become very large during turn-off when the energy is released from the inductance stored in the relay coil. However, the capacitor across the transistors C-E leads does act as a snubber, but it could also create an unwanted ringing/resonance which could be even...

Its missing the anti-parallel diode across the relay coil connection, hence the relay chatter.

Thanks!

I don't like it... :-(

It really depends how much additional work you and you moderators want. I think it is fine the way it is and ebay added to it is fine too... :-)

Well said... :-)

LOL... and have fun!

Yep...

So post up... :-)

I guess I misread your other post about the transistor amplifier configuration. If a small resistor was added to the emitter and ground, and was bypassed with a high capacity, high current poly type of capacitor, the transistor would have some built in thermal stability due to this negative...

bob, is the amplifier emitter resistor AC bypassed and is their a base resistor too? I'm guessing the Amp is being baised "B" or "AB". I would probably add a large value load resistor in parallel with the emitter - capacitor - resistor juntion. This will stabilize the transistor and bleed...