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Wednesday, October 16, 2019

Flashing Neon lamp for Soldering iron

message: How can I make a flashing neon lamp - 240 volt AC

I have been trying for 3 hours ( R-C circuits) but no success. I want to include it in my soldering iron socket to show the power is on.

Mail from HJ of UK

These circuits may help, let me know if this works.

Neon Lamp Multivibrator ASCII Circuits
    I am sure a reading of above will help make your own. do not forget, i like a feedback.


    For the 1 Meg use two 470K in Series for 230V AC, that is safer. The circuit is live, so take precautions. The 0.47 Micro Farad can be increased if you want a slow flash. If the Mains 50/60 Hz Flicker is too much, the 1 uF can be made 2 uF, or use 4 - 1N4007 as a bridge rectifier.

    Flashing Mains Neon Lamp

    Flashing Neons (NE-2 / NE-51) second from top

    User Feedback -

    R1 of 4.7M and C2 of 0.47uF Works well at 230V AC. Try your own Combination. Less than 1M may damage Neon.

    Monday, October 14, 2019

    Leakage of SSR driving AC Solenoid

    message: I have a 115vac ssr powering a solenoid only pulling a 160ma. upon activation 115vac is applied, but upon deactivation 78vac is still present. I'm told I need a bleeder resistor, but no one knows exactly what size? Can you help?

    Mail from GH USA

    When a solenoid draws 160mA, you dont need a bleeder. That itself is a bleeder. The leakage of the ssr is very less, it is mainly the current thru the snubber caps.

    The SSR cannot leak so much, Is the solenoid a simple coil solenoid or has circuitry? A coil solenoid is also a bleeder for the 1 or 2mA max AC current from caps.

    If the solenoid has some control circuit then you may need a bleeder, put a 100K 250V 1W. It also could be a defective SSR or a NC (normally closed) SSR with improper control signal.

    Read More - Solid State Relays SSR.

    SSR driving AC Solenoid - delabs

    Check if control and load circuits are isolated too, make careful measurements across the ssr. Tell me if you still are in doubt.

    See the connection diagram

    Connection Diagrams of SSR


    Battery Level Indicator

    Do you have a battery level indicator for a 24V Ni-Mh recharegeable battery source ? Prefer the display as a LED or LCD traveling bar graph.

    Mail from EY

    have a look at  BVM1 - 12 Volt Battery Voltage Monitor then let me know better, how i could help you.


    Thanks for the effort and your effort.

    I think the is good. and the instrument looks good and simple to implement. Now I am studying the circuit of solorb

    Reply from EY

    Battery Level Indicator - delabs

    Battery Level Indicator

    This circuit uses a LM339, a quad comparator. LM339 can work on single or dual supplies, it has a open collector output that can drive 15mA, low power consumption. The circuit is an untested design but it should work. I did it as many searches were made in my webpages with these keywords.